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Sn-based perovskites have intrinsic defects, such as Sn vacancies, oxidised components (Sn4+), and local lattice strain in the perovskite crystalline structure. In this study, Zn metal powder (Zn0) was introduced to reduce Sn oxidation in the solution step based on the redox potential difference. Additionally, Zn2+ was introduced in the perovskite precursor, which decreased the intrinsic defects and lattice strain of the perovskite films. The diffusion length, particularly that of the hole, increased with a reduction in the lattice strain, and Zn doping led to interfacial energy-level alignment of the perovskite and hole-transporting layers. The reduced lattice strain decreased the defect density and charge carrier recombination of perovskite devices. The power conversion efficiency of the Zn-doped Sn-based perovskite solar cell was improved to 11.39% compared to the 8.56% of the reference device. [ABSTRACT FROM AUTHOR]

Pb‐free Sn‐based perovskite solar cells (PSCs) have significant potential for application in photovoltaic devices because of their suitable bandgap, low exciton binding energy, high carrier mobility, and long diffusion length. However, their performance is hampered by several issues. Sn‐based perovskites are highly susceptible to oxidation, which induces a high concentration of defects and degrades the chemical stability of the perovskite crystals. Herein, the anion formate (HCOO−) can effectively suppress the oxidation of Sn in the pure formamidinium tin triiodide (FASnI3) perovskite without using A‐site cationic additives. Moreover, the presence of formate results in a uniform pinhole‐free perovskite film with a low trap density, reduced charge carrier recombination, and improved charge extraction. Density functional theory calculations show that formate‐treated FASnI3 has improved stability against oxidative Sn degradation. The formate‐treated PSC achieves a power conversion efficiency of 12.11% at a high open‐circuit voltage of 0.71 V. The device exhibits improved stability in ambient air in which it maintained over 80% of its initial power conversion efficiency after 180 min because oxidation is inhibited owing to the strong interaction between Sn and formate. [ABSTRACT FROM AUTHOR]

Cs-based perovskite nanocrystals (PeNCs) have been considered to be excellent emitters for perovskite light-emitting diodes (PeLEDs) due to their remarkable optoelectronic properties. Still, their poor optical properties are mainly attributed to the deeper defect states induced by the chlorine content, which has hampered the realization of the full potential of blue PeLEDs. Herein, we propose a surface passivation strategy by employing potassium thiocyanate, which is an immobile passivating material (IPM) that considerably improved the structure of the PeNCs by filling halide vacancies and uncoordinated halide sites. Indeed, the photoluminescence quantum yield of the IPM-introduced PeNCs was significantly enhanced to 74.1% compared to that of the reference PeNCs (34.0%). Besides, K+ seized the halide ions in the PeNCs, thereby resulting in excellent colloidal stability. Overall, the PeLEDs achieved an external quantum efficiency of 2.04% and an elongated operating lifetime. Our strategy provides a simple way for breaking down the hurdles limiting the practicability of PeLEDs in display applications. [ABSTRACT FROM AUTHOR]

The photovoltaic performance of inverted perovskite solar cells (PSCs) relies on effectively managing the interface between the hole extraction layer and the light‐absorbing perovskite layer. In this study, we have synthesised (4‐(3,6‐bis(methylthio)‐9H‐carbazol‐9‐yl)butyl)phosphonic acid (MeS‐4PACz), which forms a self‐assembled monolayer (SAM) on the fluorine‐doped tin oxide (FTO) electrode. The molecule‘s methylthio substituents generate a favourable interfacial dipole moment and interact with the perovskite layer. This interaction results in well‐aligned energy levels among the FTO/SAM/perovskite layers, promoting efficient hole extraction and significantly reducing carrier recombination losses. Additionally, the methylthio groups passivate iodide vacancies and interact with Pb2+ ions of the perovskite, reducing defect‐induced trap states and enhancing the crystalline growth of the perovskite layer. Consequently, inverted PSCs incorporating MeS‐4PACz achieve a power conversion efficiency of 25.13 %, along with outstanding photostability. [ABSTRACT FROM AUTHOR]

Phenyl-C 61 -butyric acid methyl ester (PCBM) can be used as a passivation material in perovskite solar cells (PeSCs) in order to reduce the trap site of the perovskite. Here, we show that a thick PCBM layer can form a smoother surface on the SnO 2 substrate, improving the grain size and reducing the microstrain of the perovskite. High-temperature annealing treatment of PCBM layer not only increases its solvent resistance to perovskite precursor or antisolvent, but also enhances its molecular alignment, resulting in improved conductivity as an electron transport layer. High-temperature annealed PCBM (HT-PCBM) effectively minimizes trap-assisted nonradiative recombination by reducing trap density in perovskite and improving the electrical properties at the interface between SnO 2 and perovskite layers. This HT-PCBM process significantly enhances the performance of the PeSCs, including the open-circuit voltage ( V OC ) from 0.39 to 0.77 V, fill factor from 52% to 65%, and power conversion efficiency (PCE) from 6.03% to 15.50%, representing substantial improvements compared to devices without PCBM. This PCE is the highest efficiency among conventional (n-i-p) Sn-Pb PeSCs reported to date. Moreover, passivating the trap sites of SnO 2 and separating the interface between the Sn-containing perovskite and the substrate effectively have improved the stability of the Sn-Pb perovskite in the n-i-p structure. The optimized best device with HT-PCBM has maintained an efficiency of over 90% for more than 300 h at 85 °C and 5000 h at room temperature in a glovebox atmosphere.