15August2020

Nano-Micro Letters

Low-Temperature Aging Provides 22% Efficient Bromine–free and Passivation Layer-free Planar Perovskite Solar Cells

Xin Wang1, Luyao Wang1, Tong Shan2, Shibing Leng1, Hongliang Zhong2, Qinye Bao3, Zheng-Hong Lu4, *, Lin-Long Deng5, *, Chun-Chao Chen1, *

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Nano-Micro Lett. (2020) 12: 84

First Online: 03 April 2020 (Article)

DOI:10.1007/s40820-020-00418-0

*Corresponding author. E-mail: zhenghong.lu@utoronto.ca (Zheng-Hong Lu), denglinlong@xmu.edu.cn (Lin-Long Deng), c3chen@sjtu.edu.cn (Chun-Chao Chen)

 

Abstract

 


Toc

The formamidinium/methylamine (FAMA) mixed halide perovskite commonly produces solar cells displaying ultrahigh (>21%) power conversion efficiencies (PCEs). Previous reports of the popular two-step sequential deposition methods of perovskite film have focused mainly on controlling the morphology of the perovskite film and its interface-for example, through the inclusion of bromine and surface passivation. In this paper, we describe a new processing pathway for the growth of a high-quality bromine-free FAMAPbI3 halide perovskites via the control of intermediate phase. Through low-temperature aging growth (LTAG) of a freshly deposited perovskite film, α-phase perovskites can be seeded in the intermediate phase and, at the same time, prevent beta-phase perovskite to nucleate. After post-annealing, large grain-size perovskites with significantly reduced PbI2 presence on the surface can be obtained, thereby, eliminate the need of additional surface passivation step. Our pristine LTAG-treated solar cells could provide PCEs of greater than 22%, close to the highest efficiencies ever recorded for planar perovskite solar cells, but prepared without elaborate use of bromine or an additional passivation layer. More importantly, when using this LTAG process, the growth of the pure alpha-phase FAMAPbI3 was highly reproducible. This much simpler means of fabricating highly efficient FA-based planar perovskite solar cells suggests that they might be one step closer to commercialization.


 

Keywords

Aging growth, Bromine-free, Passivation layer, Lead iodide, Perovskite solar cells

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