Modulating Performance and Stability of Inorganic Lead-Free Perovskite Solar Cells via Lewis-Pair Mediation

Breaking the bottleneck of lead-free perovskite solar cells through dimensionality modulation

The emerging perovskite solar cell (PSC) technology has attracted significant attention due to its superior power conversion efficiency (PCE) among the thin-film photovoltaic technologies. However, the toxicity of lead and poor stability of lead halide materials hinder their commercialization. In this case, after a decade of effort, various categories of lead-free perovskites and perovskite-like materials have been developed, including tin halide perovskites, double perovskites, defect-structured perovskites, and rudorffites. However, the performance of the corresponding devices still falls short of expectations, especially their PCE. The limitations mainly originate from either the unstable lattice structure of these materials, which causes the distortion of their octahedra, or their low dimensionality (e.g., structural and electronic dimensionality)-correlated poor carrier transport and self-trapping effect, accelerating nonradiative recombination. Therefore, understanding the relationship between the structures and performance in these emerging candidates and leveraging these insights to design or modify new lead-free perovskites is of great significance. Herein, we review the variety of dimensionalities in different categories of lead-free perovskites and perovskite-like materials and conclude that dimensionality is an important aspect among the crucial indexes that determine the performance of lead-free PSCs. In addition, we summarize the modulation of both structural and electronic dimensionality, and the corresponding enhanced optoelectronic properties in different categories. Finally, perspectives on the future development of lead-free perovskites and perovskite-like materials for photovoltaic applications are provided. We hope that this review will provide researchers with a concise overview of these emerging materials and help them leverage dimensionality to break the bottleneck in photovoltaic applications.

Nanoparticle-based immunotherapeutics: from the properties of nanocores to the differential effects of administration routes

The engagement with the immune system is one of the main cornerstones in the development of nanotechnologies for therapy and diagnostics. Recent advances have made possible the tuning of features like size, shape and biomolecular modifications that influence such interactions, however, the capabilities for immune modulation of nanoparticles are still not well defined and exploited. This review focuses on recent advances made in preclinical research for the application of nanoparticles to modulate immune responses, and the main features making them relevant for such applications. We review and discuss newest evidence in the field, which include in vivo experiments with an extensive physicochemical characterization as well as detailed study of the induced immune response. We emphasize the need of incorporating knowledge about immune response development and regulation in the design and application of nanoparticles, including the effect by parameters such as the administration route and the differential interactions with immune subsets.

Two-Dimensional Cs3Sb2I9-xClx Film with (201) Preferred Orientation for Efficient Perovskite Solar Cells

All-inorganic Sb-perovskite has become a promising material for solar cell applications owing to its air stability and nontoxic lead-free constitution. However, the poor morphology and unexpected (001) orientation of Sb-based perovskite films strongly hinder the improvement of efficiency. In this work, two-dimensional Cs₃Sb₂Cl_xI_9-x with (201) preferred orientation has been successfully fabricated by introducing thiourea (TU) to the precursor solution. The presence of the C=S functional group in TU regulates the crystallization dynamics of Cs₃Sb₂I_9-xCl_x films and generates the (201) preferred orientation of Cs₃Sb₂Cl_xI_9-x films, which could effectively improve the carrier transport and film morphology. As a result, the Cs₃Sb₂I_9-xCl_x perovskite solar cells (PSCs) delivered a power conversion efficiency (PCE) of 2.22%. Moreover, after being stored in nitrogen at room temperature for 60 days, the devices retained above 87.69% of their original efficiency. This work demonstrates a potential pathway to achieve high-efficiency Sb-based PSCs.

Synthesis of Stable Lead-Free Cs3 Sb2 (Brx I1- x )9 (0 ≤ x ≤ 1) Perovskite Nanoplatelets and Their Application in CO2 Photocatalytic Reduction

Exploring photocatalysts to foster CO₂ photoreduction into high value-added chemicals is of great significance. Lead halide perovskites (LHPs) have recently been extensively investigated as photocatalysts, owing to their facile fabrication and prominent optoelectronic properties. However, the toxicity of lead and instability will hinder their future large-scale applications. To address these challenges, a series of lead-free Sb-based all-inorganic mixed halide perovskite Cs₃ Sb₂ (Br_x I_{1- x} )₉ (0 ≤ x ≤ 1) nanoplatelets (NPLs) is synthesized. The perovskite NPLs are prepared using a ligand-assisted re-precipitation approach at 50 °C. The authors observe the tunability of their optical band gaps from 2.1 to 2.5 eV, and they can maintain the excellent stability over 120 h under heating at 100 °C or UV light irradiation. The resultant materials are employed as efficient photocatalysts for visible-light driven CO₂ reduction at the gas-solid interface. The Cs₃ Sb₂ (Br_0.7 I_0.3 )₉ perovskite NPLs afford an impressive overall yield of 27.7 µmol g^-1 for the selective photocatalytic conversion of CO₂ into CO. This study represents a significant demonstration for practical artificial photosynthesis by using LHP materials as photocatalysts.

The Effects of Temperature on the Growth of a Lead-Free Perovskite-Like (CH3NH3)3Sb2Br9 Single Crystal for An MSM Photodetector Application

We have fabricated a photodetector based on (CH₃NH₃)₃Sb₂Br₉ (MA₃Sb₂Br₉) lead-free perovskite-like single crystal, which plays an important role in the optoelectronic characteristics of the photodetector as a perovskite-like photosensitive layer. Here, MA₃Sb₂Br₉ single crystals were synthesized by an inverse temperature crystallization process with a precursor solution at three different growth temperatures, 60 °C, 80 °C, and 100 °C. As a result, a MA₃Sb₂Br₉ single crystal with an optimum growth temperature of 60 °C presented a low trap density of 2.63 × 10¹¹ cm^-3, a high charge carrier mobility of 0.75 cm² V^-1 s^-1, and excellent crystal structure and optical absorption properties. This MA₃Sb₂Br₉ perovskite-like photodetector displayed a low dark current of 8.09 × 10^-9 A, high responsivity of 0.113 A W^-1, and high detectivity of 4.32 × 10¹¹ Jones.