Interface Defects Passivation and Conductivity Improvement in Planar Perovskite Solar Cells Using Na2S-Doped Compact TiO2 Electron Transport Layers

Hao Sun; Danyan Xie; Zhen Song; Chuanhui Liang; Lingbo Xu; Xianlin Qu; Yuxin Yao; Deng Li; Hang Zhai; Kun Zheng; Can Cui; Yiying Zhao

doi:10.1021/acsami.0c03180

Interface Defects Passivation and Conductivity Improvement in Planar Perovskite Solar Cells Using Na₂S-Doped Compact TiO₂ Electron Transport Layers

ACS Appl Mater Interfaces. 2020 May 20;12(20):22853-22861. doi: 10.1021/acsami.0c03180. Epub 2020 May 11.

Authors

Hao Sun^{1

2}, Danyan Xie¹, Zhen Song², Chuanhui Liang², Lingbo Xu¹, Xianlin Qu³, Yuxin Yao¹, Deng Li², Hang Zhai², Kun Zheng³, Can Cui¹, Yiying Zhao²

Affiliations

¹ Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018, China.
² Institute of Materials, China Academy of Engineering Physics, Jiangyou 621908, China.
³ Beijing Key Laboratory of Microstructure and Properties of Solids, Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China.

PMID: 32337968
DOI: 10.1021/acsami.0c03180

Abstract

Numerous trap states and low conductivity of compact TiO₂ layers are major obstacles for achieving high power conversion efficiency and high-stability perovskite solar cells. Here we report an effective Na₂S-doped TiO₂ layer, which can improve the conductivity of TiO₂ layers, the contact of the TiO₂/perovskite interface, and the crystallinity of perovskite layers. Comprehensive investigations demonstrate that Na cations increase the conductivity of TiO₂ layers while S anions change the wettability of TiO₂ layers, thus improving the crystallinity of perovskite layers and passivate defects at the TiO₂/PVK interface. The synergetic effects of dopants lead to a champion efficiency as high as 21.25% in unencapsulated perovskite solar cells (PSCs), with much-improved stability. Our work provides new insights on anion dopants in TiO₂ layers, which is usually neglected in previous reports, and also proposes a simple approach to produce low-cost and high-performance electron transport layers for high-performance PSCs.

Keywords: additive; compact TiO2; crystallization; electron extraction; perovskite solar cells.