CO2 Plasma-Treated TiO2 Film as an Effective Electron Transport Layer for High-Performance Planar Perovskite Solar Cells

Kang Wang; Wenjing Zhao; Jia Liu; Jinzhi Niu; Yucheng Liu; Xiaodong Ren; Jiangshan Feng; Zhike Liu; Jie Sun; Dapeng Wang; Shengzhong Frank Liu

doi:10.1021/acsami.7b11329

CO₂ Plasma-Treated TiO₂ Film as an Effective Electron Transport Layer for High-Performance Planar Perovskite Solar Cells

ACS Appl Mater Interfaces. 2017 Oct 4;9(39):33989-33996. doi: 10.1021/acsami.7b11329. Epub 2017 Sep 25.

Authors

Affiliation

¹ Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Key Laboratory for Advanced Energy Devices, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University , Xi'an 710119, China.

PMID: 28914052
DOI: 10.1021/acsami.7b11329

Abstract

Perovskite solar cells (PSCs) have received great attention because of their excellent photovoltaic properties especially for the comparable efficiency to silicon solar cells. The electron transport layer (ETL) is regarded as a crucial medium in transporting electrons and blocking holes for PSCs. In this study, CO₂ plasma generated by plasma-enhanced chemical vapor deposition (PECVD) was introduced to modify the TiO₂ ETL. The results indicated that the CO₂ plasma-treated compact TiO₂ layer exhibited better surface hydrophilicity, higher conductivity, and lower bulk defect state density in comparison with the pristine TiO₂ film. The quality of the stoichiometric TiO₂ structure was improved, and the concentration of oxygen-deficiency-induced defect sites was reduced significantly after CO₂ plasma treatment for 90 s. The PSCs with the TiO₂ film treated by CO₂ plasma for 90 s exhibited simultaneously improved short-circuit current (J_SC) and fill factor. As a result, the PSC-based TiO₂ ETL with CO₂ plasma treatment affords a power conversion efficiency of 15.39%, outperforming that based on pristine TiO₂ (13.54%). These results indicate that the plasma treatment by the PECVD method is an effective approach to modify the ETL for high-performance planar PSCs.

Keywords: CO2 plasma treatment; TiO2 film; electron transport layer; perovskite; plasma-enhanced chemical vapor deposition; solar cells.