4-Terminal Inorganic Perovskite/Organic Tandem Solar Cells Offer 22% Efficiency

Dual-Interface Passivation of Wide-Bandgap Perovskite Films for Efficient Four-Terminal Perovskite-Organic Tandem Solar Cells

Interface defects in perovskite solar cells (PSCs) can significantly impair device efficiency by promoting nonradiative recombination, hindering charge transport, and facilitating ion migration. In this work, we introduce a dual-interface passivation strategy utilizing 2-(N-morpholino)ethanesulfonic acid potassium (MESK) and octylammonium iodide (OAI), targeting both the electron transport layer (ETL)/perovskite and perovskite/hole transport layer (HTL) interfaces to enhance the efficiency of wide-bandgap PSCs based on FA0.8Cs0.2Pb(I0.6Br0.4)3 with a bandgap of 1.77 eV. The sulfonic group in MESK passivates bottom interface defects through coordination with Pb ions, while the amine group in OAI interacts with Pb and halide ions to effectively passivate top interface defects. The dual-interface passivation strategy improves perovskite crystallinity, enlarges grain size, and reduces nonradiative recombination. As a result, the performance of PSCs is significantly enhanced, achieving a power conversion efficiency (PCE) of 23.69% in a four-terminal (4T) perovskite-organic tandem solar cell (TSC), which provides a promising and sustainable solution for the commercialization of TSCs.

Recent Progress on High-Efficiency Perovskite/Organic Tandem Solar Cells

Perovskite/organic tandem solar cells, as a next-generation high-efficiency photovoltaic technology, integrate the tunable bandgap characteristics of perovskite materials with the broad spectral absorption advantages of organic semiconductors, demonstrating remarkable potential to surpass the theoretical efficiency limits of single-junction cells, enhance device stability, and expand application scenarios. This architecture supports low-temperature solution processing and offers tunable bandgaps, lightweight flexibility, and ecofriendly advantages. This review systematically summarizes research progress in this field, with a primary focus on analyzing the working principles, performance optimization strategies, and key challenges of the technology. Firstly, the article discusses strategies such as defect passivation, crystallization control, and suppression of phase separation in wide-bandgap perovskite sub-cells, offering insights into mitigating open-circuit voltage losses. Secondly, for the narrow-bandgap organic sub-cells, this paper highlights the optimization strategies for both the active layer and interfacial layers, aiming to improve spectral utilization and enhance power conversion efficiency. Additionally, this paper emphasizes the optimization of optical transparency, electrical conductivity, and energy level alignment in the recombination layer, providing theoretical guidance for efficient current matching and carrier transport.

Buried Interface Regulation with TbCl3 for Highly-Efficient All-Inorganic Perovskite/Silicon Tandem Solar Cells

All-inorganic perovskite materials exhibit exceptional thermal stability and promising candidates for tandem devices, while their application is still in the initial stage. Here, a metal halide doping strategy was implemented to enhance device performance and stability for inverted CsPbI3 perovskite solar cells (PSCs), which are ideal for integration into perovskite/silicon tandem solar cells. The lanthanide compound terbium chloride (TbCl3) was employed to improve buried interface between [4-(3,6-Dimethyl-9H-carbazol-9-yl) butyl] phosphonic acid (Me-4PACz) and perovskite layer, thereby enhancing the crystallinity of CsPbI3 films and passivating non-radiative recombination defects. Thus, the inverted CsPbI3 PSCs achieved an efficiency of 18.68% and demonstrated excellent stability against water and oxygen. Meanwhile, remarkable efficiencies of 29.40% and 25.44% were, respectively, achieved in four-terminal (4T) and two-terminal (2T) perovskite/silicon mechanically tandem devices, which are higher efficiencies among reported all-inorganic perovskite-based tandem solar cells. This study presents a novel approach for fabricating highly efficient and stable inverted all-inorganic PSCs and perovskite/silicon tandem solar cells.

Synthesis and performance evaluation of ZnO/CdS photoanodes with copper sulfide (Cu2S) and carbon counter electrodes

The present study demonstrates the synthesis of compact ZnO layers using CdS sensitized on ZnO as a photoanode with copper sulfide (Cu2S) and carbon as a counter electrode (CE). In this study, a compact ZnO layer was fabricated using the simple and low-cost successive ionic layer adsorption and reaction (SILAR) method, and Cu2S CE films were synthesized using the chemical bath deposition method. Various characterizations, such as X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), confirmed the formation of ZnO and CdS sensitizations on the ZnO . UV-visible spectroscopy revealed that the bandgaps of the ZnO and Cu2S films were 3.2 and 1.3 eV, respectively. Furthermore, the morphology of the ZnO films was optimized by varying the number of SILAR cycles. Scanning electron microscopy revealed the formation of a nanorod compact layer (CL) and the porous nature of the ZnO photoanode films. However, the porosity increased with the number of SILAR cycles. Various parameters, such as the current density, voltage, fill factor, and efficiency, were measured using the J-V characteristics. The highest 0.85% efficiency was achieved by using the ZnO compact film with 30 SILAR cycles for the Cu2S CE. Furthermore, the study revealed that the Cu2S counter electrode had a higher electrocatalytic response than the carbon CE.

Progress and Application of Halide Perovskite Materials for Solar Cells and Light Emitting Devices

Halide perovskite materials have attracted worldwide attention in the photovoltaic area due to the rapid improvement in efficiency, from less than 4% in 2009 to 26.1% in 2023 with only a nanometer lever photo-active layer. Meanwhile, this nova star found applications in many other areas, such as light emitting, sensor, etc. This review started with the fundamentals of physics and chemistry behind the excellent performance of halide perovskite materials for photovoltaic/light emitting and the methods for preparing them. Then, it described the basic principles for solar cells and light emitting devices. It summarized the strategies including nanotechnology to improve the performance and the application of halide perovskite materials in these two areas: from structure-property relation to how each component in the devices affects the overall performance. Moreover, this review listed the challenges for the future applications of halide perovskite materials.

Green-Solvent Processed Blade-Coating Organic Solar Cells with an Efficiency Approaching 19% Enabled by Alkyl-Tailored Acceptors

Power-conversion-efficiencies (PCEs) of organic solar cells (OSCs) in laboratory, normally processed by spin-coating technology with toxic halogenated solvents, have reached over 19%. However, there is usually a marked PCE drop when the blade-coating and/or green-solvents toward large-scale printing are used instead, which hampers the practical development of OSCs. Here, a new series of N-alkyl-tailored small molecule acceptors named YR-SeNF with a same molecular main backbone are developed by combining selenium-fused central-core and naphthalene-fused end-group. Thanks to the N-alkyl engineering, NIR-absorbing YR-SeNF series show different crystallinity, packing patterns, and miscibility with polymeric donor. The studies exhibit that the molecular packing, crystallinity, and vertical distribution of active layer morphologies are well optimized by introducing newly designed guest acceptor associated with tailored N-alkyl chains, providing the improved charge transfer dynamics and stability for the PM6:L8-BO:YR-SeNF-based OSCs. As a result, a record-high PCE approaching 19% is achieved in the blade-coating OSCs fabricated from a green-solvent o-xylene with high-boiling point. Notably, ternary OSCs offer robust operating stability under maximum-power-point tracking and well-keep > 80% of the initial PCEs for even over 400 h. Our alkyl-tailored guest acceptor strategy provides a unique approach to develop green-solvent and blade-coating processed high-efficiency and operating stable OSCs, which paves a way for industrial development.

Enhancement in the Efficiency of Sb2 Se3 Solar Cells by Triple Function of Lithium Hydroxide Modified at the Back Contact Interface

The efficiency of antimony selenide (Sb2 Se3 ) solar cells is still limited by significant interface and deep-level defects, in addition to carrier recombination at the back contact surface. This paper investigates the use of lithium (Li) ions as dopant for Sb2 Se3 films, using lithium hydroxide (LiOH) as a dopant medium. Surprisingly, the LiOH solution not only reacts at the back surface of the Sb2 Se3 film but also penetrate inside the film along the (Sb4 Se6 )n molecular chain. First, the Li ions modify the grain boundary's carrier type and create an electric field between p-type grain interiors and n-type grain boundary. Second, a gradient band structure is formed along the vertical direction with the diffusion of Li ions. Third, carrier collection and transport are improved at the surface between Sb2 Se3 and the Au layer due to the reaction between the film and alkaline solution. Additionally, the diffusion of Li ions increases the crystallinity, orientation, surface evenness, and optical electricity. Ultimately, the efficiency of Sb2 Se3 solar cells is improved to 7.57% due to the enhanced carrier extraction, transport, and collection, as well as the reduction of carrier recombination and deep defect density. This efficiency is also a record for CdS/Sb2 Se3 solar cells fabricated by rapid thermal evaporation.

Recent progress in organic waste recycling materials for solar cell applications

Organic waste-derived solar cells (OWSC) are a classification of third-generation photovoltaic cells in which one or more constituents are fabricated from organic waste material. They are an inspirational complement to the conventional third-generation solar cell with the potential of revolutionizing our future approach to solar cell manufacture. This article provides a study and summary of solar cells that fall under the category of OWSC. OWSC own their merit to low cost of manufacturing and environmental friendliness. This review article reveals different organic waste raw materials, preparation-to-assembly methodologies, and novel approaches to solar cell manufacturing. Ideas for the optimization of the performance of OWSC are presented. The assembly configurations and photovoltaic parameters of reported OWSC are compared in detail. An overview of the trends in the research regarding OWSC in the past decade is given. Also, the advantages and disadvantages of the different solar cell technologies are discussed, and possible trends are proposed. Industrial organic waste raw materials such as paper, coal, and plastics are among the least explored and yet most attractive for solar cell fabrication. The power conversion efficiencies for the cited works are mentioned while emphasizing the products and functions of the organic waste raw materials used.

Antimony Potassium Tartrate Stabilizes Wide-Bandgap Perovskites for Inverted 4-T All-Perovskite Tandem Solar Cells with Efficiencies over 26

Wide-bandgap (WBG) perovskites have been attracting much attention because of their immense potential as a front light-absorber for tandem solar cells. However, WBG perovskite solar cells (PSCs) generally exhibit undesired large open-circuit voltage (VOC) loss due to light-induced phase segregation and severe non-radiative recombination loss. Herein, antimony potassium tartrate (APTA) is added to perovskite precursor as a multifunctional additive that not only coordinates with unbonded lead but also inhibits the migration of halogen in perovskite, which results in suppressed non-radiative recombination, inhibited phase segregation and better band energy alignment. Therefore, a APTA auxiliary WBG PSC with a champion photoelectric conversion efficiency of 20.35% and less hysteresis is presented. They maintain 80% of their initial efficiencies under 100 mW cm-2 white light illumination in nitrogen after 1,000 h. Furthermore, by combining a semi-transparent WBG perovskite front cell with a narrow-bandgap tin-lead PSC, a perovskite/perovskite four-terminal tandem solar cell with an efficiency over 26% is achieved. Our work provides a feasible approach for the fabrication of efficient tandem solar cells.

Ionic Liquid Assisted Imprint for Efficient and Stable Quasi-2D Perovskite Solar Cells with Controlled Phase Distribution

Although two-dimensional perovskite devices are highly stable, they also lead to a number of challenges. For instance, the introduction of large organic amines makes crystallization process complicated, causing problems such as generally small grain size and blocked charge transfer. In this work, imprint assisted with methylamine acetate were used to improve the morphology of the film, optimize the internal phase distribution, and enhance the charge transfer of the perovskite film. Specifically, imprint promoted the dispersion of spacer cations in the recrystallization process with the assistance of methylamine acetate, thus inhibited the formation of low-n phase induced by the aggregation of spacer cations and facilitated the formation of 3D-like phase. In this case, the corresponding quasi-2D perovskite solar cells delivered improved efficiency and exhibited superior stability. Our work provides an effective strategy to obtain uniform phase distribution for quasi-2D perovskite.