Flexible and efficient perovskite quantum dot solar cells via hybrid interfacial architecture

Fano Resonance in CO2 Reduction Catalyst Functionalized Quantum Dots

Molecular catalyst functionalized semiconductor quantum dots (QDs) are a promising modular platform for developing novel hybrid photocatalysts. The interaction between adsorbed catalyst vibrations and the QD electron intraband absorption can influence the photophysical properties of both the QD and the catalysts and potentially their photocatalysis. In CdSe QDs functionalized by the CO2 reduction catalyst, Re(CO)3(4,4'-bipyridine-COOH)Cl, we observe that the transient Fano resonance signal resulting from coupling of the catalyst CO stretching mode and the QD conduction band electron mid-IR intraband absorption appears on an ultrafast time scale and decays with the electron population, irrespective of the occurrence of photoreduced catalysts. The Fano asymmetry factor increases with an increase in the adsorbed catalyst number and a decrease in QD sizes. The latter can be attributed to an enhanced charge transfer interaction between the more strongly quantum-confined QD conduction band and catalyst LUMO levels. These results provide a more in-depth understanding of interactions in excited QD-catalyst hybrid photocatalysts.

Eco-friendly synthesis of Cs3Bi2Br9 perovskite quantum dots using castor oil as solvent and ligand for leather anti-counterfeiting

All-inorganic cesium bismuth bromide perovskite quantum dots(Cs3Bi2Br9 PQDs) have emerged as promising alternatives to lead-based perovskite quantum dots with excellent performance due to their low toxicity, drawing extensive attention over recent decades. However, challenges remain in terms of their stability and the reliance on organic solvents during the preparation process. Herein, a novel synthesis method for Cs3Bi2Br9 PQDs is introduced, utilizing eco-friendly castor oil as both the solvent and ligand (CO-Cs3Bi2Br9). These PQDs display a vivid blue emission at 430 nm, with an impressive photoluminescence quantum yield (PLQY) of 21.2%. Furthermore, they maintain 97.3% of their fluorescence intensity after 72 h of environmental exposure. The effects of various components of castor oil, including ricinoleic, oleic and linoleic acid, on crystal growth and properties of the Cs3Bi2Br9 are investigated. Significantly, the presence of conjugated double bonds in linoleic acid, when used as a solvent, results in a PLQY of up to 53% for the synthesized Cs3Bi2Br9 PQDs. Moreover, CO-Cs3Bi2Br9 PQDs are introduced into leather by a layer-by-layer self-assembly method, the bright blue fluorescent pattern can be observed in the CO-Cs3Bi2Br9/leather under ultraviolet irradiation, indicating the leather anti-counterfeiting potential of CO-Cs3Bi2Br9 PQDs. This study opens a novel pathway for the sustainable synthesis of PQDs through the utilization of castor oil-derived natural green solvents.

Surface chemistry-engineered perovskite quantum dot photovoltaics

The discovery and synthesis of colloidal quantum dots (QDs) was awarded the Nobel Prize in Chemistry in 2023. Recently, the development of bulk metal halide perovskite semiconductors has generated intense interest in their corresponding perovskite QDs. QDs, more broadly known as nanocrystals, constitute a new class of materials that differ from both molecular and bulk materials. They have rapidly advanced to the forefront of optoelectronic applications owing to their unique size-, composition-, surface- and process-dependent optoelectronic properties. More importantly, their ultrahigh surface-area-to-volume ratio enables various surface chemistry engineering strategies to tune and optimize their optoelectronic properties. Finally, three-dimensional confined QDs, offering nearly perfect photoluminescent quantum yield, slow hot-carrier cooling time, especially their colloidal synthesis and processing using industrially friendly solvents, have revolutionized the fields of electronics, photonics, and optoelectronics. Particularly, in emerging perovskite QD-based PVs, the advancement of surface chemistry has boosted the record power conversion efficiency (PCE) to 19.1% within a five-year period, surpassing all other colloidal QD photovoltaics (PVs). Given the rapid enhancement of device performances, perovskite QD PVs have attracted significant attention. Further study of semiconducting perovskite QDs will lead to advanced surface structures, a deeper understanding of halide perovskites, and enhanced PCE. In this review article, we comprehensively summarize and discuss the emerging perovskite QD PVs, providing insights into the impact of surface chemical design on their electronic coupling, dispersibility, stability and defect passivation. The limitations of current perovskite QDs mainly arise from their "soft" ionic nature and dynamic surface equilibrium, which lead to difficulties in the large-scale synthesis of monodispersed perovskite QDs and conductive inks for high-throughput printing techniques. We present that the development of surface chemistry is becoming a platform for further improving PCE, aiming to reach the 20% milestone. Additionally, we discuss integrating artificial intelligence to facilitate the mass-production of perovskite QDs for large-area, low-cost PV technology, which could help address significant energy challenges.

Hybrid halide perovskite quantum dots for optoelectronics applications: recent progress and perspective

Nanotechnology has transformed optoelectronics through quantum dots (QDs), particularly metal halide perovskite QDs (PQDs). PQDs boast high photoluminescent quantum yield, tunable emission, and excellent defect tolerance without extensive passivation. Quantum confinement effects, which refer to the phenomenon where the motion of charge carriers is restricted to a small region, produce discrete energy levels and blue shifts in these materials. They are ideal for next-generation optoelectronic devices prized for superior optical properties, low cost, and straightforward synthesis. In this review, along with the fundamental physics behind the phenomenon, we have covered advances in synthesis methods such as hot injection, ligand-assisted reprecipitation, ultrasonication, solvothermal, and microwave-assisted that enable precise control over size, shape, and stability, enhancing their suitability for LEDs, lasers, and photodetectors. Challenges include lead toxicity and cost, necessitating research into alternative materials and scalable manufacturing. Furthermore, strategies like doping and surface passivation that improve stability and emission control are discussed comprehensively, and how lead halide perovskites like CsPbBr3undergo phase transitions with temperature, impacting device performance, are also investigated. We have explored various characterization techniques, providing insights into nanocrystal properties and behaviors in our study. This review highlights PQDs' synthesis, physical and optoelectronic properties, and potential applications across diverse technologies.

Powering the Future: Opportunities and Obstacles in Lead-Halide Inorganic Perovskite Solar Cells

Efficiency, stability, and cost are crucial considerations in the development of photovoltaic technology for commercialization. Perovskite solar cells (PSCs) are a promising third-generation photovoltaic technology due to their high efficiency and low-cost potential. However, the stability of organohalide perovskites remains a significant challenge. Inorganic perovskites, based on CsPbX₃ (X = Br-/I-), have garnered attention for their excellent thermal stability and optoelectronic properties comparable to those of organohalide perovskites. Nevertheless, the development of inorganic perovskites faces several hurdles, including the need for high-temperature annealing to achieve the photoactive α-phase and their susceptibility to transitioning into the nonphotoactive δ-phase under environmental stressors, particularly moisture. These challenges impede the creation of high-efficiency, high-stability devices using low-cost, scalable manufacturing processes. This review provides a comprehensive background on the fundamental structural, physical, and optoelectronic properties of inorganic lead-halide perovskites. It discusses the latest advancements in fabricating inorganic PSCs at lower temperatures and under ambient conditions. Furthermore, it highlights the progress in state-of-the-art inorganic devices, particularly those manufactured in ambient environments and at reduced temperatures, alongside simultaneous advancements in the upscaling and stability of inorganic PSCs.

Ultrafast broadband spectroscopy of widely spread excitonic features in WSe2 nanosheets

The performance of an optoelectronic device is largely dependent on the light harvesting properties of the active material as well as the dynamic behaviour of the photoexcited charge carriers upon absorption of light. Recently, atomically thin two-dimensional transition metal dichalcogenides (2D TMDCs) have garnered attention as highly prospective materials for advanced ultrathin solar cells and other optoelectronic applications, owing to their strong interaction with electromagnetic radiation, substantial optical conductivity, and impressive charge carrier mobility. WSe2 is one such extremely promising solar energy material. It has absorption throughout the UV-Vis-NIR region with the existence of four excitonic features, just like MoS2 and WS2. However, stability issues and the absence of any robust synthetic route limit their practical applications. Herein, we have successfully synthesized atomically thin stable WSe2 nanosheets using a very effective colloidal hot injection method and further studied the optical properties of this material using femtosecond transient absorption spectroscopy. We probed all four excitonic features of WSe2 spread throughout the visible region. The dynamics of the high-energy excitons were found to be distinctively slower when compared to their band edge counterparts, adding an additional advantage in optoelectronic applications. We delved further into the factors governing exciton dynamics within WSe2, uncovering the strong influence of the electronic band structure. Importantly, our study highlights the importance of all four excitonic features in a 2D TMDC material, which emerge in the system irrespective of the excitation wavelength and influence each other.

Structural Mechanisms of Quasi-2D Perovskites for Next-Generation Photovoltaics

Quasi-two-dimensional (2D) perovskite embodies characteristics of both three-dimensional (3D) and 2D perovskites, achieving the superior external environment stability structure of 2D perovskites alongside the high efficiency of 3D perovskites. This effect is realized through critical structural modifications in device fabrication. Typically, perovskites have an octahedral structure, generally ABX3, where an organic ammonium cation (A') participates in forming the perovskite structure, with A'(n) (n = 1 or 2) sandwiched between A(n-1)B(n)X(3n+1) perovskite layers. Depending on whether A' is a monovalent or divalent cation, 2D perovskites are classified into Ruddlesden-Popper perovskite or Dion-Jacobson perovskite, each generating different structures. Although each structure achieves similar effects, they incorporate distinct mechanisms in their formation. And according to these different structures, various properties appear, and additive and optimizing methods to increase the efficiency of 3D perovskites also exist in 2D perovskites. In this review, scientific understanding and engineering perspectives of the quasi-2D perovskite is investigated, and the optimal structure quasi-2D and the device optimization is also discussed to provide the insight in the field.

High Efficiency (>10%) AgBiS2 Colloidal Nanocrystal Solar Cells with Diketopyrrolopyrrole-Based Polymer Hole Transport Layer

Silver bismuth disulfide (AgBiS2) colloidal nanocrystals (CNCs) have emerged as ecofriendly photoactive materials with excellent photoconductivity and high absorption coefficients, in compliance with the restriction of hazardous substances (RoHS) guidelines. To maximize the theoretical potential of AgBiS2 CNC solar cells, a new diketopyrrolopyrrole (DPP)-based polymer, BD2FCT, optimized as a hole transport layer (HTL), is developed. This asymmetric thiophene-rich polymer HTL effectively complements the optical absorption spectrum of CNCs and forms a homogeneous layer atop the CNCs, facilitating favorable vertical charge transfer through intrinsic molecular packing. Furthermore, the BD2FCT HTL aligns energetically with AgBiS2, significantly reducing charge recombination at the CNC/HTL interfaces and enhancing charge extraction and photocurrent generation across the entire optical absorption spectrum. These characteristics are further optimized through precise molecular engineering. Additionally, a low-bandgap acceptor, IEICO-4F, is structurally incorporated with the BD2FCT polymer to further improve charge funneling and complementary absorption. Transient absorption spectroscopy reveals enhanced hole transfer from CNC to BD2FCT-29DPP:IEICO-4F, resulting in reduced charge recombination and efficient charge extraction. Consequently, a BD2FCT-based AgBiS2 CNC solar cell achieves a power conversion efficiency (PCE) of 10.1%, demonstrating significant improvements in short-circuit current density (JSC) and fill factor (FF).

A Brief Review of Perovskite Quantum Dot Solar Cells: Synthesis, Property and Defect Passivation

Perovskite quantum dot solar cells (PQDSCs), as the promising candidate for the next generation of solar cell, have garnered the significant attention over the past decades. However, the performance and stability of PQDSCs are highly dependent on the properties of interfaces between the perovskite quantum dots (PQDs) and the other layers in the device. This work provides a brief overview of PQDSCs, including the synthesis of PQDs, the characteristics and preparation methods of PQDs, the photoelectric properties as the light absorption layer and optimization methods for PQDSCs with high efficiency. Future directions and potential applications are also highlighted.

Dual-Phase Ligand Engineering Enables 18.21% FAPbI3 Quantum Dot Solar Cells

Formamidinium lead triiodide (FAPbI3) perovskite quantum dot (PQD) are promising candidate for high-performing quantum dot photovoltaic due to its narrow bandgap, high ambient stability, and long carrier lifetime. However, the carrier transport blockage and nonradiative recombination loss, originating from the high-dielectric ligands and defects/trap states on the FAPbI3 PQD surface, significantly limit the efficiency and stability of its photovoltaic performance. In this work, through exploring dual-site molecular ligands, namely 2-thiophenemethylammonium iodide (2-TM) and 2-thiopheneethylammonium iodide (2-TE), a dual-phase synergistic ligand exchange (DSLE) protocol consisting of both solution-phase and solid-state ligand engineering is demonstrated. The DSLE strategy effectively replaces the native long insulating ligands and simultaneously passivate surface defects in hybrid FAPbI3 PQDs, leading to enhanced electronic coupling for efficient charge transport. Consequently, the FAPbI3 PQD solar cell based on DSLE strategy achieves a notable enhanced efficiency from 15.43% to 17.79% (2-TM) and 18.21% (2-TE), respectively. Besides, both 2-TM and 2-TE engineered devices exhibit enhanced stability, maintaining over 80% of its initial efficiency after aging in ambient environment (20-30% humidity, 25 °C) for over 1400 h. It believes these findings will provide a new protocol to precisely regulate the surface chemistry of hybrid PQDs toward high-performance optoelectronic applications.

Electrostatic Harmonization for Superior Charge Extraction at Interface for Stable High-Efficiency FAPbI3 Quantum Dots Solar Cells

Organic-inorganic formamidinium lead triiodide (FAPbI3) hybrid perovskite quantum dots (QDs) have garnered considerable attention in the photovoltaic field due to their narrow bandgap, exceptional environmental stability, and prolonged carrier lifetime. Unfortunately, their insulating ligands and surface vacancy defects pose significant obstacles to efficient charge transfer across device interfaces. In this work, an electrostatic harmonization strategy at the interface using a donor-acceptor dipole molecular attachment to achieve enhanced charge separation capabilities on the QD surface is ventured. On the basis of theoretical study and experimental evaluation, it has gained a comprehensive understanding of dipole-induced electronic restructuring at the quantum dot interfaces. It reveals that 3-fluoro-4-iodopyridine as a dipole source with appropriate energy levels and a high dipole moment effectively fills surface iodine vacancies (VI-), leading to rapid separation of photoexcited charge carriers. Particularly enhanced hole mobility and hydrophobicity are achieved through strong electronegative effects of fluorine and iodine. Consequently, the FAPbI3 QD solar cells achieve a power conversion efficiency as high as 14.11% with exceptional long-term stability in ambient. These perceptions provide effective interface engineering means for the hybrid perovskite QDs to advance their potential in high-performance optoelectronic applications.

Coupling and Energy Transfer between an Exciton in a Semiconductor Quantum Dot and a Surface Plasmon in a Metal Nanoparticle

The coupling between excitons in semiconductors or molecules and metal nanoparticles has been well-studied, primarily for nanoparticles in their ground electronic state. However, less attention has been given to exciton-nanoparticle interactions when the nanoparticle generates surface plasmons upon incident excitation. In this study, we explore the coupling and energy transfer dynamics between an exciton and the surface plasmon of a metal nanoparticle, forming a "plexciton". Significant mutual energy exchange between the exciton and the plasmon leads to unexpected effects on the exciton lifetime and coupling strength. The interaction at varying wavelengths, orientations, magnitudes, and phases was studied. Our results show that the exciton decay rate can be quenched entirely when the plasmon's energy compensates for that of the exciton radiative decay, even at separation distances of several hundred nanometers. These findings highlight the impact of surface plasmons on exciton dynamics, opening new possibilities for enhancing charge carrier dynamics in coupled systems.

Liquid bidentate ligand for full ligand coverage towards efficient near-infrared perovskite quantum dot LEDs

Perovskite quantum dots (PQDs) show promise in light-emitting diodes (LEDs). However, near-infrared (NIR) LEDs employing PQDs exhibit inferior external quantum efficiency related to the PQD emitting in the visible range. One fundamental issue arises from the PQDs dynamic surface: the ligand loss and ions migration to the interfacial sites serve as quenching centers, resulting in trap-assisted recombination and carrier loss. In this work, we developed a chemical treatment strategy to eliminate the interface quenching sites and achieve high carrier utilization. We employ a bidentate and liquid agent (Formamidine thiocyanate, FASCN) with tight binding to suppress the ligand loss and the formation of interfacial quenching sites: the FASCN-treated films exhibit fourfold higher binding energy than the original oleate ligands. Furthermore, the short ligands (carbon chain <3) enable the treated films to show eightfold higher conductivity; and the liquid characteristics of FASCN avoid the use of high polar solvents and guarantee better passivation. The high conductivity ensures efficient charge transportation, enabling PQD-based NIR-LEDs to have a record-low voltage of 1.6 V at 776 nm. Furthermore, the champion EQE of the treated LEDs is ~23%: this is twofold higher than the control, and represents the highest among reported PQD-based NIR-LEDs.

Surface Doping to Suppress Iodine Ion Migration for Stable FAPbI3 Perovskite Quantum Dot Solar Cells

Formamidine lead iodide (FAPbI3) quantum dots (QDs) have attracted great attention as a new generation of photovoltaic material due to their long carrier diffusion length, benign ambient stability, and light-harvesting ability. However, its large surface area with inherent thermodynamic instability and highly defective ionic termination are still major obstacles to fabricating high-performance devices. Herein, a metallic ion dopant is developed to post-treat FAPbI3 QDs immediately after their fabrication by using a metal-glutamate salt solution. Both experimental and theoretical results show that alkaline (earth) metal ions (Mg2+, Na+, and K+) in their glutamate salt can not only successfully substitute insulating long-chain ligands to form thinner ligand shells but inhibit the formation of iodine vacancies on the surface of QDs. As a result, the glutamate-Mg based solar cell exhibits a champion efficiency of 13.48%, and the other two solar cells treated by glutamate alkaline metal salts (Na+ and K+) achieve photoelectrical conversion efficiencies of 13.26% and 11.88%, respectively, all of which are higher than of control cell with an efficiency of 11.58%. Therefore, this substantial progress provides intuitive cognition and guidance for the improvement of photoelectric performance and the commercial application of quantum dot solar cells.

PCBM Constructing Heterojunction for Efficient CsPbI3 Perovskite Quantum Dot Solar Cells

CsPbI3 perovskite quantum dots (PQDs) have emerged as promising photovoltaic materials for third-generation solar cells, owing to their superior optoelectronic properties. Nevertheless, the performance of CsPbI3 PQD solar cells is primarily hindered by low carrier extraction efficiency, largely due to the insulative ligands. In this study, we introduced a semiconductor molecule, [6,6]-phenyl C61 butyric acid methyl ester (PCBM), onto the surfaces of CsPbI3 PQDs as surface ligands to enhance photogenerated charge extraction. The results indicate that PCBM accelerates carrier separation in CsPbI3 PQDs by forming a type II heterojunction, and also modulates the energy level of CsPbI3 PQDs by altering surface dipole moments. Additionally, we established an energy-level gradient alignment in the PCBM/CsPbI3 PQD heterojunction absorber layer, which was found to effectively promote carrier extraction and reduce carrier recombination loss in PQD solar cells. Ultimately, the PQD solar cells incorporating this novel structure achieved a power conversion efficiency of 14.23%, a significant improvement compared to 12.69% achieved by solar cells with a traditional structure, thus demonstrating the strong potential of this approach for high-performance PQD solar cells.

Photoluminescence Switching in Quantum Dots Connected with Carboxylic Acid and Thiocarboxylic Acid End-Group Diarylethene Molecules

We contrast the switching of photoluminescence (PL) of PbS quantum dots (QDs) cross-linked with photochromic diarylethene molecules with different end groups, 4,4'-(1-cyclopentene-1,2-diyl)bis[5-methyl-2-thiophenecarboxylic acid] (1C) and 4,4'-(1-cyclopentene-1,2-diyl)bis[5-methyl-2-thiophenethiocarboxylic acid] (2T). Our results show that the QDs cross-linked with the carboxylic acid end group molecules (1C) exhibit a greater amount of switching in photoluminescence intensity compared to QDs cross-linked with the thiocarboxylic acid end group (2T). We also demonstrate that regardless of the molecule used, greater switching amounts are observed for smaller quantum dots. Varying these parameters allows for the fabrication of photoswitches with tunable PL change. We relate these observations to the differences in the HOMO energy levels between the QDs and the photochromic molecules. Our findings demonstrate how the size of the QDs and the energy levels of the linker ligands influences the charge tunneling rate and thus the PL switching performance in tunneling-based photoswitches.

Micrometer-Resolution Fluorescence and Lifetime Mappings of CsPbBr3 Nanocrystal Films Coupled with a TiO2 Grating

Enhancing light emission from perovskite nanocrystal (NC) films is essential in light-emitting devices, as their conventional stacks often restrict the escape of emitted light. This work addresses this challenge by employing a TiO2 grating to enhance light extraction and shape the emission of CsPbBr3 nanocrystal films. Angle-resolved photoluminescence (PL) demonstrated a 10-fold increase in emission intensity by coupling the Bloch resonances of the grating with the spontaneous emission of the perovskite NCs. Fluorescence lifetime imaging microscopy (FLIM) provided micrometer-resolution mapping of both PL intensity and lifetime across a large area, revealing a decrease in PL lifetime from 8.2 ns for NC films on glass to 6.1 ns on the TiO2 grating. Back focal plane (BFP) spectroscopy confirmed how the Bloch resonances transformed the unpolarized, spatially incoherent emission of NCs into polarized and directed light. These findings provide further insights into the interactions between dielectric nanostructures and perovskite NC films, offering possible pathways for designing better performing perovskite optoelectronic devices.

Carbon Dots Infused 3D Printed Cephalopod Mimetic Bactericidal and Antioxidant Hydrogel for Uniaxial Mechano-Fluorescent Tactile Sensor

Cephalopods use stretchy skin and dynamic color-tuning organs for visual communication and camouflage. Inspired by these natural mechanisms, a fluorescent biomaterial for deformation-induced illumination and optical communication is proposed. This is the first report of 3D printed soft biomaterials infused with carbon dots hydrothermally derived from chitosan and benzalkonium chloride. These biomaterials exhibit a comprehensive array of properties, including significant uniaxial stretching, near-instantaneous response to tactile stimuli and pH, UV resistance, antibacterial, antioxidant, noncytotoxicity, and highlighting their potential as mechano-optical materials for biomedical applications. The hydrogel's durability is evaluated by cyclic stretching, folding, rolling, and twisting tests to ensure its integrity and good signal-to-noise ratio. The diffusion mechanism is determined by water imbibition kinetics, network parameters, and time-dependent breathing. Overcoming the common limitations of short lifespans and complex manufacturing processes in existing soft hybrids, this work demonstrates a straightforward method to produce durable, energy-independent, mechano-optical hydrogel. Combined with investigations, molecular dynamic modeling is used to understand the interactions of hydrogel components.

CaF2 Nanoparticle-Induced γ-CsPbI2.81Br0.19 Heterogeneous Crystallization for High-Efficiency Flexible All-Inorganic Perovskite Solar Cells

All-inorganic CsPbI3 films necessitate higher annealing temperatures for high-quality crystallization. Consequently, the conventional low-temperature solution approach often results in poor crystallization in flexible CsPbI3 films, significantly degrading the optoelectronic performance and stability of flexible perovskite solar cells (f-PSCs). Herein, a heterogeneous CaF2 nanocrystal seed-induced strategy has been successfully utilized to achieve enhanced crystallization of a flexible CsPbI2.81Br0.19 film. Due to their good lattice match with the perovskite material, CaF2 nanoparticles can decrease the critical Gibbs free energy of CsPbI2.81Br0.19 perovskite nucleation, thereby accelerating γ-phase CsPbI2.81Br0.19 crystallization at low temperatures. This leads to an improved crystalline quality of the flexible perovskite film at low temperatures, which minimizes defects and enhances the stability of f-PSCs. The CsPbI2.81Br0.19 f-PSCs achieved a champion power conversion efficiency of 15.03% and demonstrated mechanical stability, retaining 98.1% of their initial efficiency even after 60 000 bending cycles with a curvature radius of 5 mm.

Special-point approach for optical absorption coefficient calculations on two-dimensional self-assemblies of type-II perovskite quantum dots

All-inorganic perovskite quantum dots with the usual cubic shape have emerged as a successful and low-cost alternative to electronically functional nanomaterials motivating various fields of applications, including high-efficiency photovoltaics. Here, we present an efficient and almost analytic approach for optical absorption coefficient calculation on self-assembled perovskite quantum dot films with type-II band alignment. The approach takes advantage of the special point technique for integration over the two-dimensional Brillouin zone, which minimizes the computational cost. The set of special wave-vector points is generated using the Monkhorst and Pack method. The optical absorption spectrum for phenyl-C60-butyric acid methyl ester (PCBM)/CsPbI3quantum dot films is computed, in good agreement with the experiment assuming a homogeneous linewidth of 50 meV and considering a ten special-point set. We show that light absorption in these systems is a cooperative optoelectronic property resulting from the quantum-mechanical coupling between perovskite nanocubes, leading to extended system states. The generality of this approach makes it suitable for calculating the optical absorption coefficient in a broad class of perovskite quantum dot systems.

Understanding the Potential of Light Absorption in Dots-in-Host Semiconductors

The outstanding physical properties of dots-in-host (QD@Host) hetero semiconductors demand detailed methods to fundamentally understand the best routes to optimize their potentialities for different applications. In this work, a 4-band k.p-based method was developed for rock-salt quantum dots (QDs) that describes the complete optical properties of arbitrary QD@Host systems, trailblazing the way for the full optoelectronic analysis of quantum-structured solar cells. Starting with the determination of the QD bandgap and validation against well-established literature results, the electron transition rate is then computed and analyzed against the main system parameters. This is followed by a multiparameter optimization, considering intermediate band solar cells as a promising application, where the best QD configuration was determined, together with the corresponding QD@Host absorption spectrum, in view of attaining the theoretical maximum efficiency (∼50%) of this photovoltaic technology. The results show the creation of pronounced sub-bandgap absorption due to the electronic transitions from/to the quantum-confined states, which enables a much broader exploitation of the sunlight spectrum.

Strategies To Achieve Long-Term Stability in Lead Halide Perovskite Nanocrystals and Its Optoelectronic Applications

The lead halide perovskite (LHP) nanocrystals (NCs) research area is flourishing due to their exceptional properties and great potential for a wide range of applications in optoelectronics and photovoltaics. Yet, despite the momentum in the field, perovskite devices are not yet ready for commercialization due to degradation caused by intrinsic phase transitions and external factors such as moisture, temperature, and ultraviolet (UV) light. To attain long-term stability, we analyze the origin of instabilities and describe different strategies such as surface modification, encapsulation, and doping for long-term viability. We also assess how these stabilizing strategies have been utilized to obtain optoelectronic devices with long-term stability. This Mini-Review also outlines the future direction of each strategy for producing highly efficient and ultrastable LHP NCs for sustainable applications.

A multifunctional phenylphosphinamide additive for stable flexible inverted perovskite solar cells

The multifunctional phenylphosphinamide additive is used in flexible inverted perovskite solar cells to release tensile strain and increase the toughness of the perovskite film, achieving enhanced device efficiency and stability.

InP QDs modified GaAs/PEDOT:PSS hybrid solar cell with efficiency over 15

GaAs heterojunction solar cells are known as promising substitutions for traditional GaAs solar cells for their low cost and performance potential. Nevertheless, the further performance enhancement is hindered by insufficient spectral absorption and nonradioactive recombination. In this work, an InP quantum dot (QD) modified GaAs/PEDOT:PSS solar cell is designed to enhance spectrum utilization and suppress the nonradioactive carriers loss and the solar cell efficiency at 15.08% is achieved. Furthermore, InP QDs used in this work are synthesized by a novel hydrothermal method. During the synthesis process, β-cyclodextrin (β-cyc) was introduced into the reactants and acted as a reaction cell, isolating water and oxygen, enabling the reaction to proceed in ambient air. InP QDs synthesized by this method can achieve band engineering by altering reactant ratios, thereby effectively serving as both a Luminescent Solar Concentrator (LSC) and a Front Surface Field (FSF) in GaAs/PEDOT:PSS solar cells. This work demonstrates an inspiring way to synthesize InP QDs and optimize the performance of GaAs hybrid solar cells.

Quantum Dots for Resistive Switching Memory and Artificial Synapse

Memristor devices for resistive-switching memory and artificial synapses have emerged as promising solutions for overcoming the technological challenges associated with the von Neumann bottleneck. Recently, due to their unique optoelectronic properties, solution processability, fast switching speeds, and low operating voltages, quantum dots (QDs) have drawn substantial research attention as candidate materials for memristors and artificial synapses. This review covers recent advancements in QD-based resistive random-access memory (RRAM) for resistive memory devices and artificial synapses. Following a brief introduction to QDs, the fundamental principles of the switching mechanism in RRAM are introduced. Then, the RRAM materials, synthesis techniques, and device performance are summarized for a relative comparison of RRAM materials. Finally, we introduce QD-based RRAM and discuss the challenges associated with its implementation in memristors and artificial synapses.

Recent Advances in Structure Design and Application of Metal Halide Perovskite-Based Gas Sensor

Metal halide perovskites (MHPs) are emerging gas-sensing materials and have attracted considerable attention in gas sensors due to their unique bandgap structure and tunable optoelectronic properties. The past decade has witnessed significant developments in the gas-sensing field; however, their intrinsic structural instability and ambiguous gas-sensing mechanisms hamper their practical applications. Herein, we summarize the recent advances in MHP-based gas sensors. The physicochemical properties of MHPs are discussed at first. The structure design, including dimension design and engineering design, is overviewed as well as their fabrication methods, and we put forward our insights into the gas-sensing mechanism of MHPs. It is believed that enhanced understanding of gas-sensing mechanisms of MHPs are helpful for their application as gas-sensing materials, and structure design can enhance their stability, sensing sensitivity, and selectivity to target gases as gas sensors. Subsequently, the latest developments in MHP-based gas sensors are summarized according to their different application scenarios. Finally, we conclude with the current status and challenges in this field and propose future perspectives.

Band Engineering of Perovskite Quantum Dot Solids for High-Performance Solar Cells

CsPbI3 perovskite quantum dot (PQD) shows high potential for next-generation photovoltaics due to their tunable surface chemistry, good solution-processability and unique photophysical properties. However, the remained long-chain ligand attached to the PQD surface significantly impedes the charge carrier transport within the PQD solids, thereby predominantly influencing the charge extraction of PQD solar cells (PQDSCs). Herein, a ligand-induced energy level modulation is reported for band engineering of PQD solids to improve the charge extraction of PQDSCs. Detailed theoretical calculations and systemic experimental studies are performed to comprehensively understand the photophysical properties of the PQD solids dominated by the surface ligands of PQDs. The results reveal that 4-nitrobenzenethiol and 4-methoxybenzenethiol molecules with different dipole moments can firmly anchor to the PQD surface through the thiol group to modulate the energy levels of PQDs, and a gradient band structure within the PQD solid is subsequently realized. Consequently, the band-engineered PQDSC delivers an efficiency of up to 16.44%, which is one of the highest efficiencies of CsPbI3 PQDSCs. This work provides a feasible avenue for the band engineering of PQD solids by tuning the surface chemistry of PQDs for high-performing solar cells or other optoelectronic devices.

Surface ligand manipulation enables ∼15% efficient MAPbI3 perovskite quantum dot solar cells

We reported a surface ligand manipulation strategy for hybrid MAPbI3 perovskite quantum dots (PeQDs) using methylamine iodide (MAI), methylamine thiocyanate (MASCN) and methylamine acetate (MAAc) salts. After MAI salt post-treatment, a record high efficiency of 14.98% was obtained for MAPbI3 PeQD solar cells together with enhanced ambient stability.

Hybrid Amino Acid Ligand-Regulated Excited Dynamics of Highly Luminescent Perovskite Quantum Dots for Bright White Light-Emitting Diodes

Organic-inorganic hybrid perovskite quantum dots (QDs) have garnered significant research interest owing to their unique structure and optoelectronic properties. However, their poor optical performance in ambient air remains a significant limitation, hindering their advancement and practical applications. Herein, three amino acids (valine, threonine and cysteine) were chosen as surface ligands to successfully prepare highly luminescent CH3NH3PbBr3 (MAPbBr3) QDs. The morphology and XRD results suggest that the inclusion of the amino acid ligands enhances the octahedral structure of the QD solutions. Moreover, the observed blue-shifted phenomenon in the photoluminescence (PL) aligns closely with the blue-shifted phenomenon observed in the ultraviolet-visible (UV-Vis) absorption spectra, attributed to the quantum confinement effect. The time-resolved spectra indicated that the introduction of the amino acid ligands successfully suppressed non-radiative recombination, consequently extending the fluorescence lifetime of the MAPbBr3 QDs. The photoluminescence quantum yields (PLQYs) of the amino acid-treated MAPbBr3 QDs are increased by 94.8%. The color rendering index (CRI) of the produced white light-emitting diode (WLED) is 85.3, with a correlated color temperature (CCT) of 5453 K. Our study presents a novel approach to enhancing the performance of perovskite QDs by employing specially designed surface ligands for surface passivation.

Lattice Mismatch at the Heterojunction of Perovskite Solar Cells

Lattice mismatch significantly influences microscopic transport in semiconducting devices, affecting interfacial charge behavior and device efficacy. This atomic-level disordering, often overlooked in previous research, is crucial for device efficiency and lifetime. Recent studies have highlighted emerging challenges related to lattice mismatch in perovskite solar cells, especially at heterojunctions, revealing issues like severe tensile stress, increased ion migration, and reduced carrier mobility. This review systematically discusses the effects of lattice mismatch on strain, material stability, and carrier dynamics. It also includes detailed characterizations of these phenomena and summarizes current strategies including epitaxial growth and buffer layer, as well as explores future solutions to mitigate mismatch-induced issues. We also provide the challenges and prospects for lattice mismatch, aiming to enhance the efficiency and stability of perovskite solar cells, and contribute to renewable energy technology advancements.

A Universal Approach Toward Intrinsically Flexible All-Inorganic Perovskite-Gel Composites with Full-Color Luminescence

The combination of all-inorganic perovskites (PVSKs) and polymers allows for free-standing flexible optoelectronic devices. However, solubility difference of the PVSK precursors and concerns over the compatibility between polymer carriers and PVSKs imply a great challenge to incorporate different kinds of PVSKs into polymer matrices by the same manufacturing process. In this work, PVSK precursors are introduced into poly(2-hydroxyethyl acrylate) (PHEA) hydrogels in sequence, in which the PVSK-gel composites are achieved with full-color emissions by simply varying the precursor species. Moreover, it is found that CsBr has a higher interaction energy with the (111) plane of CsPbBr3 than the (110) plane; thus, the CsPbBr3 crystals with a shape of truncated cube and tetragon are observed during the CsPbBr3-Cs4PbBr6 phase transition over time. The PVSK-gel composites feature excellent bendability, elasticity, and stretchable deformation (tensile strain > 500%), which allows for 3D printing emissive customized stereoscopic architectures with shape-memory features.

Perovskite Colloidal Nanocrystal Solar Cells: Current Advances, Challenges, and Future Perspectives

The power conversion efficiencies (PCEs) of polycrystalline perovskite (PVK) solar cells (SCs) (PC-PeSCs) have rapidly increased. However, PC-PeSCs are intrinsically unstable without encapsulation, and their efficiency drops during large-scale production; these problems hinder the commercial viability of PeSCs. Stability can be increased by using colloidal PVK nanocrystals (c-PeNCs), which have high surface strains, low defect density, and exceptional crystal quality. The use of c-PeNCs separates the crystallization process from the film formation process, which is preponderant in large-scale fabrication. Consequently, the use of c-PeNCs has substantial potential to overcome challenges encountered when fabricating PC-PeSCs. Research on colloidal nanocrystal-based PVK SCs (NC-PeSCs) has increased their PCEs to a level greater than those of other quantum-dot SCs, but has not reached the PCEs of PC-PeSCs; this inferiority significantly impedes widespread application of NC-PeSCs. This review first introduces the distinctive properties of c-PeNCs, then the strategies that have been used to achieve high-efficiency NC-PeSCs. Then it discusses in detail the persisting challenges in this domain. Specifically, the major challenges and solutions for NC-PeSCs related to low short-circuit current density Jsc are covered. Last, the article presents a perspective on future research directions and potential applications in the realm of NC-PeSCs.

Interfacial Heterojunction Enables High Efficient PbS Quantum Dot Solar Cells

Colloidal quantum dots (CQDs) are promising optoelectronic materials for solution-processed thin film optoelectronic devices. However, the large surface area with abundant surface defects of CQDs and trap-assisted non-radiative recombination losses at the interface between CQDs and charge-transport layer limit their optoelectronic performance. To address this issue, an interface heterojunction strategy is proposed to protect the CQDs interface by incorporating a thin layer of polyethyleneimine (PEIE) to suppress trap-assisted non-radiative recombination losses. This thin layer not only acts as a protective barrier but also modulates carrier recombination and extraction dynamics by forming heterojunctions at the buried interface between CQDs and charge-transport layer, thereby enhancing the interface charge extraction efficiency. This enhancement is demonstrated by the shortened lifetime of carrier extraction from 0.72 to 0.46 ps. As a result, the resultant PbS CQD solar cells achieve a power-conversion-efficiency (PCE) of 13.4% compared to 12.2% without the heterojunction.

All-Round Passivation Strategy Yield Flexible Perovskite/CuInGaSe2 Tandem Solar Cells with Efficiency Exceeding 26.5

The perovskite/Cu(InGa)Se2 (CIGS) tandem solar cells (TSCs) presents a compelling technological combination poised for the next generation of flexible and lightweight photovoltaic (PV) tandem devices, featuring a tunable bandgap, high power conversion efficiency (PCE), lightweight flexibility, and enhanced stability and durability. Over the years, the imperative to enhance the performance of wide bandgap (WBG) perovskite solar cells (PSCs) has grown significantly, particularly in the context of a flexible tandem device. In this study, an all-round passivation strategy known as Dual Passivation at Grains and Interfaces (DPGI) is introduced for WBG PSCs in perovskite/CIGS tandem structures. The implementation of DPGI is tailored to improve film crystallinity and passivate defects across the solar cell structure, leading to a substantial performance enhancement for WBG PSCs. Subsequently, both rigid and flexible tandem devices are assembled. Impressively, a fully flexible 4T perovskite/CIGS TSCs is successfully fabricated with a PCE of 26.57%, making it the highest value in this field and highlighting its potential applications in the next generation of flexible lightweight PV tandem devices.

A high temperature in situ optical probe for colloidal nanocrystal synthesis

We report on the fabrication and utilization of a robust high-temperature (>300 °C), adjustable-path-length, vacuum-tolerant, configurable, in situ optical probe, which interfaces with widely used chemical glassware via a 14/20 ground glass joint. This probe allows for high-speed reaction monitoring of colloidal semiconductor nanocrystal solutions at temperatures that were previously inaccessible. We demonstrate this capability by monitoring the hot-injection synthesis of CdSe quantum dots via UV-Vis absorption spectroscopy at 380 °C with a time resolution of ∼10 ms, with the primary limitation being the acquisition and data saving rate of the commercial spectrometer used. We further demonstrate that this probe can also be used for in situ photoluminescence measurements. This system is generally applicable to harsh solution environments where optical monitoring of reaction progress is desirable and/or necessary.

New Nanophotonics Approaches for Enhancing the Efficiency and Stability of Perovskite Solar Cells

Over the past decade, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has experienced a remarkable ascent, soaring from 3.8% in 2009 to a remarkable record of 26.1% in 2023. Many recent approaches for improving PSC performance employ nanophotonic technologies, from light harvesting and thermal management to the manipulation of charge carrier dynamics. Plasmonic nanoparticles and arrayed dielectric nanostructures have been applied to tailor the light absorption, scattering, and conversion, as well as the heat dissipation within PSCs to improve their PCE and operational stability. In this review, it is begin with a concise introduction to define the realm of nanophotonics by focusing on the nanoscale interactions between light and surface plasmons or dielectric photonic structures. Prevailing strategies that utilize resonance-enhanced light-matter interactions for boosting the PCE and stability of PSCs from light trapping, carrier transportation, and thermal management perspectives are then elaborated, and the resultant practical applications, such as semitransparent photovoltaics, colored PSCs, and smart perovskite windows are discussed. Finally, the state-of-the-art nanophotonic paradigms in PSCs are reviewed, and the benefits of these approaches in improving the aesthetic effects and energy-saving character of PSC-integrated buildings are highlighted.

High-efficiency upconversion luminescence in UCNPs/CsPbBr3 nanocomposites enhanced by silver nanoparticles

Upconversion nanocomposites with multiple light-emitting centers have attracted great attention as functional materials, but their low efficiency limits their further applications. Herein, a novel, to the best of our knowledge, system for nanocomposites consisting of upconversion nanoparticles (UCNPs) and perovskite quantum dots (PeQDs) assembled with Ag nanoparticles (NPs) is proposed. Upconversion luminescence (UCL) operation from PeQDs is triggered by near-infrared (NIR) sensitization through Förster resonance energy transfer (FRET) and photon reabsorption (PR). Especially, the photoluminescence (PL) emission efficiency is found to be significantly enhanced due to the increased energy transfer efficiency and radiative decay rate in the UCNPs/CsPbBr3 nanocomposites. The results offer new opportunities to improve the UCL properties of perovskites and open new development in the fields of LED lighting, solar cells, biomedicine, and so on.

CdSe/ZnS quantum dots as a booster in the active layer of distributed ternary organic photovoltaics

Organic solar cells are a promising candidate for practical use because of their low material cost and simple production procedures. The challenge is selecting materials with the right properties and how they interrelate in the context of manufacturing the device. This paper presents studies on CdSe/ZnS nanodots as dopants in a polymer-fullerene matrix for application in organic solar cells. An assembly of poly(3-hexylthiophene-2,5-diyl) and 6,6-phenyl-C71-butyric acid methyl ester was used as the active reference layer. Absorption and luminescence spectra as well as the dispersion relations of refractive indices and extinction coefficient were investigated. The morphologies of the thin films were studied with atomic force microscopy. The chemical boundaries of the ternary layers were determined by Raman spectroscopy. Based on UPS studies, the energy diagram of the potential devices was determined. The resistivity of the layers was determined using impedance spectroscopy. Simulations (General-Purpose Photovoltaic Device Model) showed a performance improvement in the cells with quantum dots of 0.36-1.45% compared to those without quantum dots.

Fluidization and Application of Carbon Nano Agglomerations

Carbon nanomaterials are unique with excellent functionality and diverse structures. However, agglomerated structures are commonly formed because of small-size effects and surface effects. Their hierarchical assembly into micro particles enables carbon nanomaterials to break the boundaries of classical Geldart particle classification before stable fluidization under gas-solid interactions. Currently, there are few systematic reports regarding the structural evolution and fluidization mechanism of carbon nano agglomerations. Based on existing research on carbon nanomaterials, this article reviews the fluidized structure control and fluidization principles of prototypical carbon nanotubes (CNTs) as well as their nanocomposites. The controlled agglomerate fluidization technology leads to the successful mass production of agglomerated and aligned CNTs. In addition, the self-similar agglomeration of individual ultralong CNTs and nanocomposites with silicon as model systems further exemplify the important role of surface structure and particle-fluid interactions. These emerging nano agglomerations have endowed classical fluidization technology with more innovations in advanced applications like energy storage, biomedical, and electronics. This review aims to provide insights into the connections between fluidization and carbon nanomaterials by highlighting their hierarchical structural evolution and the principle of agglomerated fluidization, expecting to showcase the vitality and connotation of fluidization science and technology in the new era.

High-Performance Optoelectronic Gas Sensing Based on All-Inorganic Mixed-Halide Perovskite Nanocrystals with Halide Engineering

Gas sensors are of great interest to portable and miniaturized sensing technologies with applications ranging from air quality monitoring to explosive detection and medical diagnostics, but the existing chemiresistive NO2 sensors still suffer from issues such as poor sensitivity, high operating temperature, and slow recovery. Herein, a high-performance NO2 sensors based on all-inorganic perovskite nanocrystals (PNCs) is reported, achieving room temperature operation with ultra-fast response and recovery time. After tailoring the halide composition, superior sensitivity of ≈67 at 8 ppm NO2 is obtained in CsPbI2 Br PNC sensors with a detection level down to 2 ppb, which outperforms other nanomaterial-based NO2 sensors. Furthermore, the remarkable optoelectronic properties of such PNCs enable dual-mode operation, i.e., chemiresistive and chemioptical sensing, presenting a new and versatile platform for advancing high-performance, point-of-care NO2 detection technologies.

Enhancing photoluminescence performance of perovskite quantum dots with plasmonic nanoparticles: insights into mechanisms and light-emitting applications

Perovskite quantum dots (QDs) are considered as promising materials for numerous optoelectronic applications due to their narrow emission spectra, high color purity, high photoluminescence quantum yields (PLQYs), and cost-effectiveness. Herein, we synthesized various types of perovskite QDs and incorporated Au nanoparticles (NPs) to systematically investigate the impact of plasmonic effects on the photoluminescence performance of perovskite QDs. The PLQYs of the QDs are enhanced effectively upon the inclusion of Au NPs in the solutions, with an impressive PLQY approaching 99% achieved. The PL measurements reveal that the primary mechanism behind the PL improvement is the accelerated rate of radiative recombination. Furthermore, we integrate perovskite QDs and Au NPs, which function as color conversion layers, with blue light-emitting diodes (LEDs), achieving a remarkable efficiency of 140.6 lm W-1. Additionally, we prepare photopatternable thin films of perovskite QDs using photocrosslinkable polymers as the matrix. Microscale patterning of the thin films is accomplished, indicating that the addition of plasmonic NPs does not adversely affect their photopatternable properties. Overall, our research not only elucidates the underlying mechanisms of plasmonic effects on perovskite QDs but presents a practical method for enhancing their optical performance, paving the way for next-generation optoelectronic applications, including high-definition micro-LED panels.

Facile Ligand Exchange of Ionic Ligand-Capped Amphiphilic Ag2S Nanocrystals for High Conductive Thin Films

A surface ligand modification of colloidal nanocrystals (NCs) is one of the crucial issues for their practical applications because of the highly insulating nature of native long-chain ligands. Herein, we present straightforward methods for phase transfer and ligand exchange of amphiphilic Ag2S NCs and the fabrication of highly conductive films. S-terminated Ag2S (S-Ag2S) NCs are capped with ionic octylammonium (OctAH+) ligands to compensate for surface anionic charge, S2-, of the NC core. An injection of polar solvent, formamide (FA), into S-Ag2S NCs dispersed in toluene leads to an additional envelopment of the charged S-Ag2S NC core by FA due to electrostatic stabilization, which allows its amphiphilic nature and results in a rapid and effective phase transfer without any ligand addition. Because the solvation by FA involves a dissociation equilibrium of the ionic OctAH+ ligands, controlling a concentration of OctAH+ enables this phase transfer to show reversibility. This underlying chemistry allows S-Ag2S NCs in FA to exhibit a complete ligand exchange to Na+ ligands. The S-Ag2S NCs with Na+ ligands show a close interparticle distance and compatibility for uniformly deposited thin films by a simple spin-coating method. In photoelectrochemical measurements with stacked Ag2S NCs on ITO electrodes, a 3-fold enhanced current response was observed for the ligand passivation of Na+ compared to OctAH+, indicating a significantly enhanced charge transport in the Ag2S NC film by a drastically reduced interparticle distance due to the Na+ ligands.

Kidney injury contributes to edema of zebrafish larvae caused by quantum dots

Edema represents a notable outcome in fishes exposed to aquatic pollutants, yet the underlying etiology remains inadequately understood. This investigation delves into the etiological factors of edema formation in 7 days post fertilization (dpf) zebrafish larvae following their exposure to InP/ZnS quantum dots (QDs), which was chosen as a prototypical edema inducer. Given the fundamental role of the kidney in osmoregulation, we used transgenic zebrafish lines featuring fluorescent protein labeling of the glomerulus, renal tubule, and blood vessels, in conjunction with histopathological scrutiny. We identified the pronounced morphological and structural aberrations within the pronephros. By means of tissue mass spectrometry imaging and hyperspectral microscopy, we discerned the accumulation of InP/ZnS QDs in the pronephros. Moreover, InP/ZnS QDs impeded the renal clearance capacity of the pronephros, as substantiated by diminished uptake of FITC-dextran. InP/ZnS QDs also disturbed the expression levels of marker genes associated with kidney development and osmoregulatory function at the earlier time points, which preceded the onset of edema. These results suggest that impaired fluid clearance most likely resulting from pronephros injury contributes to the emergence of zebrafish edema. Briefly, our study provides a perspective: the kidney developmental injury induced by exogenous substances may regulate edema in a zebrafish model.

In situ and General Multidentate Ligand Passivation Achieves Efficient and Ultra-Stable CsPbX3 Perovskite Quantum Dots for White Light-Emitting Diodes

Inorganic CsPbX3 perovskite quantum dots (PeQDs) show great potential in white light-emitting diodes (WLEDs) due to excellent optoelectronic properties, but their practical application is hampered by low photoluminescence quantum yield (PLQY) and especially poor stability. Herein,  we developed an in-situ and general multidentate ligand passivation strategy that allows for CsPbX3 PeQDs not only near-unit PLQY, but significantly improved stability against storage, heat, and polar solvent. The enhanced optical property arises from high effectiveness of the multidentate ligand, diethylenetriaminepentaacetic acid (DTPA) with five carboxyl groups, in passivating uncoordinated Pb2+ defects and suppressing nonradiative recombination. First-principles calculations reveal that the excellent stability is attributed to tridentate binding mode of DTPA that remarkably boosts the adsorption capacity to PeQD core. Finally, combining the green and red PeQDs with blue chip,  we demonstrated highly luminous WLEDs with distinctly enhanced operation stability, a wide color gamut of 121.3% of national television system committee, standard white light of (0.33,0.33) in CIE 1931, and tunable color temperatures from warm to cold white light readily by emitters' ratio. This study provides an operando yet general approach to achieve efficient and stable PeQDs for WLEDs and accelerates their progress to commercialization.

Synthesis and hybridization of CuInS2 nanocrystals for emerging applications

Copper indium sulfide (CuInS2) is a ternary A(I)B(III)X(VI)2-type semiconductor featuring a direct bandgap with a high absorption coefficient. In attempts to explore their practical applications, nanoscale CuInS2 has been synthesized with crystal sizes down to the quantum confinement regime. The merits of CuInS2 nanocrystals (NCs) include wide emission tunability, a large Stokes shift, long decay time, and eco-friendliness, making them promising candidates in photoelectronics and photovoltaics. Over the past two decades, advances in wet-chemistry synthesis have achieved rational control over cation-anion reactivity during the preparation of colloidal CuInS2 NCs and post-synthesis cation exchange. The precise nano-synthesis coupled with a series of hybridization strategies has given birth to a library of CuInS2 NCs with highly customizable photophysical properties. This review article focuses on the recent development of CuInS2 NCs enabled by advanced synthetic and hybridization techniques. We show that the state-of-the-art CuInS2 NCs play significant roles in optoelectronic and biomedical applications.

Comprehensive guidance for optimizing the colloidal quantum dot (CQD) Perovskite solar cells: experiment and simulation

CsPbI3 perovskite quantum dots (CPQDs) have received great attention due to their potential in large-scale applications. Increasing the efficiency of CPQDs solar cells is an important issue that is addressed in this paper. Here, we have simulated a 14.61% colloidal CPQD solar cell with the least fitting parameter that shows the accuracy of the following results. The absorber layer properties are varied and different power conversion efficiency (PCE) is achieved for the new device. The results show that colloidal CsPbI3 material properties have a significant effect on the PCE of the device. Finally, the optimized parameters for the absorber layer are listed and the optimum efficiency of 29.88% was achieved for this case. Our results are interesting that help the researchers to work on CsPbI3 materials for the achievement of highly efficient, stable, large-scale, and flexible CPQDs solar cells.

Enhanced Interface Compatibility by Ionic Dendritic Molecules To Achieve Efficient and Stable Perovskite Solar Cells

Poly(3-hexylthiophene) (P3HT) represents a promising hole transport material for emerging perovskite solar cells (PSCs) due to its appealing merits of high thermal stability and appropriate hydrophobicity. Nonetheless, large energy losses at the P3HT/perovskite interface lead to unsatisfied efficiency and stability of the devices. Herein, two ionic dendritic molecules, 3,3'-(2,7-bis(3,6-bis(bis(4-methoxyphenyl)amino)-9H-carbazol-9-yl)-9H-fluorene-9,9-diyl)bis(N,N,N-trimethylpropan-1-aminium) iodide and 3,3'-(2,7-bis(bis(4-(bis(4-methoxyphenyl)amino)phenyl)amino)-9H-fluorene-9,9-diyl)bis(N,N,N-trimethylpropan-1-aminium) iodide, namely, MPA-Cz-FAI and MPA-PA-FAI, are rationally designed as the interlayer to enhance interfacial compatibility. The dendritic backbone with conjugated structure endows the hole transport layer with high conductivity, derived from the more ordered microstructure with larger crystallization and higher connectivity of domain zones. Besides, a better energy level alignment is established between P3HT and perovskite, which enhances the charge extraction and transport yield. In addition, the peripheral methoxy groups enable effective defect passivation at the interface to suppress nonradiative recombination and the quaternary ammonium iodide serving as side chains enable efficient interfacial hole extraction contributing to enhanced charge collection yield. As a result, the dopant-free P3HT-based PSCs modified with MPA-Cz-PAI deliver a champion efficiency of 19.7%, significantly higher than that of the control devices (15.4%). More encouragingly, the unencapsulated devices demonstrate competitive environmental stability by retaining over 85% of its initial efficiency after 1500 h of storage under humid conditions (70% relative humidity). This work provides an effective molecular design strategy for interface engineering, envisaging a bright prospect for the further development of efficient and stable perovskite solar cells.

Synergistically Enhanced Photocatalytic Degradation by Coupling Slow-Photon Effect with Z-Scheme Charge Transfer in CdS QDs/IO-TiO2 Heterojunction

Lower light absorption and faster carrier recombination are significant challenges in photocatalysis. This study introduces a novel approach to address these challenges by anchoring cadmium sulfide quantum dots (CdS QDs) on inverse opal (IO)-TiO₂, which increases light absorption and promotes carriers' separation by coupling slow-photon effect with Z-scheme charge transfer. Specifically, the IO-TiO₂ was created by etching a polystyrene opal template, which resulted in a periodic structure that enhances light absorption by reflecting light in the stop band. The size of CdS quantum dots (QDs) was regulated to achieve appropriate alignment of energy bands between CdS QDs and IO-TiO₂, promoting carrier transfer through alterations in charge transfer modes and resulting in synergistic-amplified photocatalysis. Theoretical simulations and electrochemical investigations demonstrated the coexistence of slow-photon effects and Z-scheme transfer. The system's photodegradation performance was tested using rhodamine B as a model. This novel hierarchical structure of the Z-scheme heterojunction exhibits degradability 7.82 and 4.34 times greater than pristine CdS QDs and IO-TiO₂, respectively. This study serves as a source of inspiration for enhancing the photocatalytic capabilities of IO-TiO₂ and broadening its scope of potential applications.

Development of luminescence carbon quantum dots for metal ions detection and photocatalytic degradation of organic dyes from aqueous media

In the present study, fish scale waste was used for the organic synthesis of luminescence CQDs by the hydrothermal method. The impact of CQDs on improved photocatalytic degradation of organic dyes and metal ions detection is examined in this study. The synthesized CQDs had a variety of characteristics that were detected, such as crystallinity, morphology, functional groups, and binding energies. The luminescence CQDs showed outstanding photocatalytic effectiveness for the destruction of methylene blue (96.5%) and reactive red 120 dye (97.8%), respectively after 120 min exposure to visible light (420 nm). The high electron transport properties of the CQDs edges, which make it possible to efficiently separate electron-hole pairs, are attributed to the enhanced photocatalytic activity of the CQDs. These degradation results prove that the CQDs are the outcome of a synergistic interaction between visible light (adsorption); a potential mechanism is also suggested, and the kinetics is analyzed to use a pseudo-first-order model. Additionally, the metal ions detection of CQDs was studied by various metal ions (Hg²⁺, Fe²⁺, Cu²⁺, Ni²⁺, and Cd²⁺) in an aqueous solution and results revealed that the PL intensity of CQDs in presence of cadmium ions decreased. Studies show that the organic fabrication of CQDs are effective photocatalyst and may one day serve as the ideal material to reduce water pollution.

Emerging Trends of Carbon-Based Quantum Dots: Nanoarchitectonics and Applications

Carbon-based quantum dots (QDs) have emerged as a fascinating class of advanced materials with a unique combination of optoelectronic, biocompatible, and catalytic characteristics, apt for a plethora of applications ranging from electronic to photoelectrochemical devices. Recent research works have established carbon-based QDs for those frontline applications through improvements in materials design, processing, and device stability. This review broadly presents the recent progress in the synthesis of carbon-based QDs, including carbon QDs, graphene QDs, graphitic carbon nitride QDs and their heterostructures, as well as their salient applications. The synthesis methods of carbon-based QDs are first introduced, followed by an extensive discussion of the dependence of the device performance on the intrinsic properties and nanostructures of carbon-based QDs, aiming to present the general strategies for device designing with optimal performance. Furthermore, diverse applications of carbon-based QDs are presented, with an emphasis on the relationship between band alignment, charge transfer, and performance improvement. Among the applications discussed in this review, much focus is given to photo and electrocatalytic, energy storage and conversion, and bioapplications, which pose a grand challenge for rational materials and device designs. Finally, a summary is presented, and existing challenges and future directions are elaborated.