We report the addition of a small amount of Pb(SCN)2 into PbI2 in a two-step solution method. The resulting CH3NH3PbI(3-x)(SCN)x perovskite films present larger-sized crystals and fewer traps than CH3NH3PbI3. Their planar solar cells exhibit a maximum power conversion efficiency of 11.07% with remarkably high reproducibility and good stability.

Recently, organic metal halide perovskites have emerged as one of the most promising photoactive materials in the field of photovoltaics.

A self-assembled monolayer of 4-aminobenzoic acid (PABA) modified TiO2 layer improved the interfacial compatibility and the quality of the above-deposited perovskite, leading to the power conversion efficiency of the device to be enhanced to 10.58%.

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In hybrid organic-inorganic perovskite solar cells (PSCs), interfacial engineering can efficiently improve the photovoltaic performance. In this work, the planar π-conjugated porphyrin, zinc(II) 5,10,15,20-tetrakis[5-(p-acetylthiopentyloxy)phenyl]porphyrin, was developed to modify the interface between poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and perovskite. The modified devices increased their highest power conversion efficiency (PCE) to 14.05% relative to 11.35% for the reference devices without modification. Such enhancement in efficiency is mainly attributed to the improved open-circuit voltage (Voc) and fill factor (FF), which benefit from fast hole-extraction and low charge recombination after the employment of well-aligned interlayer.

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Perovskite materials and their optoelectronic devices have attracted intensive attentions in recent years. However, it is difficult to further improve the performance of perovskite devices due to the poor stability and the intrinsic deep level trap states (DLTS), which are caused by surface dangling bonds and grain boundaries. Herein, the CH 3 NH 3 PbBr 3 perovskite microcrystal is encapsulated by a dense Al 2 O 3 layer to form a microenvironment. Through optical measurement, it is found that the structure of perovskite can be healed by itself even under high temperature and long-time laser illumination. The DLTS density decreases nearly an order of magnitude, which results in 4-14 times enhancement of light emission. The observation is ascribed to the micron-level environment, which serves as a self-sufficient high-vacuum growth chamber, where the components of the perovskite are completely retained when sublimated and the decomposed atoms can re-arrange after thermal treatment. The modified structure showing high thermal stability is able to maintain excellent optical and lasing stability up to 2 years. This discovery provides a new idea and perspective for improving the stability of perovskite and can be of practical interest for perovskite device application.

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