Advanced partial nucleation for single-phase FA0.92MA0.08PbI3-based high-efficiency perovskite solar cells

Abstract

To date, extensive research has been carried out, with considerable success, on the development of highperformance perovskite solar cells (PSCs). Owing to its wide absorption range and remarkable thermal stability, the mixedcation perovskite FA x MA 1−x PbI 3 (formamidinium/methylammonium lead iodide) promises high performance. However, the ratio of the mixed cations in the perovskite film has proved difficult to control with precursor solution. In addition, the FA x MA 1−x PbI 3 films contain a high percentage of MA + and suffer from serious phase separation and high trap states, resulting in inferior photovoltaic performance. In this study, to suppress phase separation, a post-processing method was developed to partially nucleate before annealing, by treating the as-prepared intermediate phase FAI-PbI 2-DMSO (DMSO: dimethylsulfoxide) with mixed FAI/MAI solution. It was found that in the final perovskite, FA 0.92 MA 0.08 PbI 3 , defects were substantially reduced because the analogous molecular structure initiated ion exchange in the post-processed thin perovskite films, which advanced partial nucleation. As a result, the increased light harvesting and reduced trap states contributed to the enhancement of open-circuit voltage and short-circuit current. The PSCs produced by the post-processing method presented reliable reproducibility, with a maximum power conversion efficiency of 20.80% and a degradation of~30% for 80 days in standard atmospheric conditions.

Boosting optoelectronic performance of MAPbI3 perovskite solar cells via ethylammonium chloride additive engineering

“…PL measurements provide direct insight into the non-radiative excitons' decay performance. The control film showed non-uniform peak intensity triggered by large trap flux, which contributed to poor carrier mobility [42,43]. Meanwhile, the EACl-2.5% film exhibited uniform and high peak intensity, suggesting a minimized non-radiative exciton decay, which was almost an order of magnitude higher than that of the EACl-0% film.…”

Enhanced crystallization in the CsPbBr3 all-inorganic perovskite via an advanced nucleation method

“…During the crystallization process, the advanced nucleation process can swift the nucleation rate and make the final layer more uniform. 18 As shown in Fig. 1b, the scanning electron microscopy (SEM) image of the CsPbBr 3 film based on PbBr 2 without CsBr (control) shows numerous gaps between grain boundaries.…”

Ion exchange for halide perovskite: From nanocrystal to bulk materials

“…Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim [150] ) a Cs x FA 1-x PbI 3 film, in which the N-methylimidazole could improve the crystallization process and result into increased grain size. Dai et al [148] introduced mixed-cation post-substitution to realize "partial nucleation" before annealing, which effectively promoted the analogous ionexchange process on a pre-deposited intermediate film via intramolecular cation substitution. The defects density was substantially reduced in the final FA 0.92 MA 0.08 PbI 3 perovskite because the analogous molecular structure initiated ion exchange and advanced partial nucleation in the post-processed perovskite film.…”