Plasma-Exposure-Induced Mobility Enhancement of LiTFSI-Doped Spiro-OMeTAD Hole Transport Layer in Perovskite Solar Cells and Its Impact on Device Performance

Hao Qu; Gao Zhao; Yumeng Wang; Lijuan Liang; Long Zhang; Wenya Liu; Chunmei Zhang; Chen Niu; Yi Fang; Jiazi Shi; Jiushan Cheng; Dongdong Wang

doi:10.3390/ma12193142

Plasma-Exposure-Induced Mobility Enhancement of LiTFSI-Doped Spiro-OMeTAD Hole Transport Layer in Perovskite Solar Cells and Its Impact on Device Performance

Materials (Basel). 2019 Sep 26;12(19):3142. doi: 10.3390/ma12193142.

Authors

Hao Qu^{1

2}, Gao Zhao^{3

4}, Yumeng Wang^{5

6}, Lijuan Liang⁷, Long Zhang^{8

9}, Wenya Liu^{10

11}, Chunmei Zhang^{12

13}, Chen Niu^{14

15}, Yi Fang¹⁶, Jiazi Shi¹⁷, Jiushan Cheng^{18

19}, Dongdong Wang²⁰

Affiliations

¹ Beijing Key Laboratory of Printing & Packaging Materials and Technology, Beijing Institute of Graphic Communication, Beijing 102600, China. qh18810592168@163.com.
² Lab of Plasma Physics and Materials, School of Printing and Packaging Engineering, Beijing Institute of Graphic Communication, Beijing 102600, China. qh18810592168@163.com.
³ Lab of Plasma Physics and Materials, School of Printing and Packaging Engineering, Beijing Institute of Graphic Communication, Beijing 102600, China. zhaohengyu369@163.com.
⁴ School of physics and electrical engineering, Zhengzhou Normal University, Zhengzhou 450044, China. zhaohengyu369@163.com.
⁵ Beijing Key Laboratory of Printing & Packaging Materials and Technology, Beijing Institute of Graphic Communication, Beijing 102600, China. wangym2019@yeah.net.
⁶ Lab of Plasma Physics and Materials, School of Printing and Packaging Engineering, Beijing Institute of Graphic Communication, Beijing 102600, China. wangym2019@yeah.net.
⁷ Beijing Key Laboratory of Printing & Packaging Materials and Technology, Beijing Institute of Graphic Communication, Beijing 102600, China. bjldllj@hotmail.com.
⁸ Beijing Key Laboratory of Printing & Packaging Materials and Technology, Beijing Institute of Graphic Communication, Beijing 102600, China. longzhang1993@foxmail.com.
⁹ Lab of Plasma Physics and Materials, School of Printing and Packaging Engineering, Beijing Institute of Graphic Communication, Beijing 102600, China. longzhang1993@foxmail.com.
¹⁰ Beijing Key Laboratory of Printing & Packaging Materials and Technology, Beijing Institute of Graphic Communication, Beijing 102600, China. liuwenya654321@163.com.
¹¹ Lab of Plasma Physics and Materials, School of Printing and Packaging Engineering, Beijing Institute of Graphic Communication, Beijing 102600, China. liuwenya654321@163.com.
¹² Beijing Key Laboratory of Printing & Packaging Materials and Technology, Beijing Institute of Graphic Communication, Beijing 102600, China. zhangchunmei@bigc.edu.cn.
¹³ Lab of Plasma Physics and Materials, School of Printing and Packaging Engineering, Beijing Institute of Graphic Communication, Beijing 102600, China. zhangchunmei@bigc.edu.cn.
¹⁴ Beijing Key Laboratory of Printing & Packaging Materials and Technology, Beijing Institute of Graphic Communication, Beijing 102600, China. niuchen2010@163.com.
¹⁵ Lab of Plasma Physics and Materials, School of Printing and Packaging Engineering, Beijing Institute of Graphic Communication, Beijing 102600, China. niuchen2010@163.com.
¹⁶ Beijing Engineering Research Center of Printed Electronics, Beijing Institute of Graphic Communication, Beijing 102600, China. fangyi@bigc.edu.cn.
¹⁷ Beijing Key Laboratory of Printing & Packaging Materials and Technology, Beijing Institute of Graphic Communication, Beijing 102600, China. shijiazi@bigc.edu.cn.
¹⁸ Beijing Key Laboratory of Printing & Packaging Materials and Technology, Beijing Institute of Graphic Communication, Beijing 102600, China. jscheng@bigc.edu.cn.
¹⁹ Lab of Plasma Physics and Materials, School of Printing and Packaging Engineering, Beijing Institute of Graphic Communication, Beijing 102600, China. jscheng@bigc.edu.cn.
²⁰ Beijing Key Laboratory of Printing & Packaging Materials and Technology, Beijing Institute of Graphic Communication, Beijing 102600, China. dongdongwang@bigc.edu.cn.

Abstract

2,2',7,7'-Tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9'-spirobifluorene (spiro-OMeTAD) film currently prevails as hole transport layer (HTL) employed in perovskite solar cells (PSCs). However, the standard preparation method for spin-coated, Lithium bis(trifluoromethylsulfony) imide (LiTFSI)-doped, spiro-OMeTAD HTL depends on a time-consuming and uncontrolled oxidation process to gain desirable electrical conductivity to favor device operation. Our previous work demonstrated that ~10 s oxygen or oxygen containing gas discharge plasma exposure can oxidize spiro-OMeTAD HTL effectively and make PSCs work well. In this communication, hole-only devices are fabricated and in-situ current density-voltage measurements are performed to investigate the change in hole mobility of LiTFSI-doped spiro-OMeTAD films under plasma exposure. The results reveal that hole mobility values can be increased averagely from ~5.0 × 10^-5 cm²V^-1s^-1 to 7.89 × 10^-4 cm²V^-1s^-1 with 7 s O₂ plasma exposure, and 9.33 × 10^-4 cm²V^-1s^-1 with 9 s O₂/Ar plasma exposure. The effects on the photovoltaic performance of complete PSC devices are examined, and optical emission spectroscopy (OES) is used for a diagnostic to explain the different exposure effects of O₂ and O₂/Ar plasma. High efficiency, fine controllability and good compatibility with current plasma surface cleaning techniques may make this method an important step towards the future commercialization of photovoltaic technologies employing spiro-OMeTAD hole transport material.

Keywords: hole mobility; perovskite solar cell; plasma exposure; spiro-OMeTAD.