Bifunctional Ultrathin PCBM Enables Passivated Trap States and Cascaded Energy Level toward Efficient Inverted Perovskite Solar Cells

Dongyang Li; Weiguang Kong; Haichao Zhang; Deng Wang; Wang Li; Changwen Liu; Hong Chen; Weidong Song; Fangliang Gao; Abbas Amini; Baomin Xu; Shuti Li; Chun Cheng

doi:10.1021/acsami.0c02837

Bifunctional Ultrathin PCBM Enables Passivated Trap States and Cascaded Energy Level toward Efficient Inverted Perovskite Solar Cells

ACS Appl Mater Interfaces. 2020 Apr 29;12(17):20103-20109. doi: 10.1021/acsami.0c02837. Epub 2020 Apr 14.

Authors

Dongyang Li^{1

2}, Weiguang Kong³, Haichao Zhang¹, Deng Wang¹, Wang Li¹, Changwen Liu¹, Hong Chen¹, Weidong Song⁴, Fangliang Gao², Abbas Amini⁵, Baomin Xu^{1

6

7}, Shuti Li², Chun Cheng^{1

6

7}

Affiliations

¹ Department of Materials Science and Engineering, Southern University of Science and Technology (SUSTech), Shenzhen 518055, P. R. China.
² Laboratory of Nanophotonic Functional Materials and Devices, Institute of Semiconductor, South China Normal University, Guangzhou 510631, P. R. China.
³ Hebei Key Laboratory of Optic-Electronic Information and Materials and National-Local Joint Engineering Laboratory of New Energy Photoelectric Devices, College of Physics Science and Technology, Hebei University, Baoding 071002, P. R. China.
⁴ College of Applied Physics and Materials, Wuyi University, 22 Dongcheng Village, Jiangmen 529020, Guangdong, P. R. China.
⁵ Center for Infrastructure Engineering, Western Sydney University, Kingswood, NSW 275, Australia.
⁶ Shenzhen Engineering Research and Development Center for Flexible Solar Cells, Southern University of Science and Technology (SUSTech), Shenzhen 518055, P. R. China.
⁷ Guangdong Provincial Key Laboratory of Energy Materials for Electric Power, Southern University of Science and Technology (SUSTech), Shenzhen 518055, P. R. China.

PMID: 32252523
DOI: 10.1021/acsami.0c02837

Abstract

Inverted perovskite solar cells (PSCs) with a C₆₀ framework are known for their common drawback of low power conversion efficiency (PCE) of <20% because of nonradiative recombination and inefficient charge transport at their perovskite interfaces. Here, we report an ultrathin [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as a cap layer on perovskite films to overcome this issue. Such a functional cap layer efficiently passivates trap states and establishes a gradient energy level alignment onto perovskite, facilitating the efficient charge transfer and extraction. The as-fabricated inverted PSCs capped with such ultrathin PCBM exhibit a record PCE of 20.07%. After the storage under a N₂ atmosphere for more than 500 h, the PCE of PSCs retains over 85% of its initial level. Our work provides an effective method to upgrade inverted PSCs with the C₆₀ framework with improved efficiency and stability.

Keywords: cascaded energy level; defect passivation; high efficiency; interface engineering; inverted perovskite solar cell; ultrathin PCBM.