1. ACS Appl. Mater. Interfaces | Research Article

Approximately 800-nm-Thick Pinhole-Free Perovskite Films via Facile Solvent Retarding Process for Efficient Planar Solar Cells
Zhongcheng Yuan, Yingguo Yang, Zhongwei Wu, Sai Bai, Weidong Xu, Tao Song, Xingyu Gao, Feng Gao, and Baoquan Sun

ACS Appl. Mater. Interfaces, 2016, 8 (50), pp 34446–34454 dol: 10.1021/acsami.6b12637


Device performance of organometal halide perovskite solar cells significantly depends on the quality and thickness of perovskite absorber films. However, conventional deposition methods often generate pinholes within ∼300 nm-thick perovskite films, which are detrimental to the large area device manufacture. Here we demonstrated a simple solvent retarding process to deposit uniform pinhole free perovskite films with thicknesses up to ∼800 nm. Solvent evaporation during the retarding process facilitated the components separation in the mixed halide perovskite precursors, and hence the final films exhibited pinhole free morphology and large grain sizes. In addition, the increased precursor concentration after solvent-retarding process led to thick perovskite films. Based on the uniform and thick perovskite films prepared by this convenient process, a champion device efficiency up to 16.8% was achieved. We believe that this simple deposition procedure for high quality perovskite films around micrometer thickness has a great potential in the application of large area perovskite solar cells and other optoelectronic devices.

1. Applied Physics Letters | Research Article

Inhomogeneous degradation in metal halide perovskites

Rong Yang, Li Zhang, Yu Cao, Yanfeng Miao, You Ke, Yingqiang Wei, Qiang Guo, Ying Wang, Zhaohua Rong, Nana Wang, Renzhi Li, Jianpu Wang, Wei Huang, and   Feng Gao
Appl. Phys. Lett. 111, 073302 (2017); doi: 10.1063/1.4999630

Although the rapid development of organic-inorganic metal halide perovskite solar cells has led to certified power conversion efficiencies of above 20%, their poor stability remains a major challenge, preventing their practical commercialization. In this paper, we investigate the intrinsic origin of the poor stability in perovskite solar cells by using a confocal fluorescence microscope. We find that the degradation of perovskite films starts from grain boundaries and gradually extend to the center of the grains. Firmly based on our findings, we further demonstrate that the device stability can be significantly enhanced by increasing the grain size of perovskite crystals. Our results have important implications to further enhance the stability of optoelectronic devices based on metal halide perovskites.