Kalium persulfate as a low-cost and effective dopant for spiro-OMeTAD in high performance and stable planar perovskite solar cells

• DOI: 10.1016/j.electacta.2021.138233
• Publication Date: 2021-03-26T10:29:58Z
• Authors: Weihai Sun; Pengqiang Yuan; Shibo Wang; Yitian Du; Jinjun Zou; Fengxian Cao; Zhang Lan; Jihuai Wu
• Keywords: 01 natural sciences; 7. Clean energy; 0104 chemical sciences

Abstract Hole transport materials (HTMs) play an important role for achieving high performance and stable perovskite solar cells (PSCs). Although the state-of-the-art HTM, spiro-OMeTAD, has been successfully applied in PSCs, it exhibits an inferior conductivity and hole mobility, which hampers its future application in commercial PSCs. In this study, a common and strong inorganic oxidant, kalium persulfate (KPS), is introduced as a p-type dopant into spiro-OMeTAD for PSCs with a regular n-i-p architecture. By the introduction of KPS into spiro-OMeTAD films, we systematically investigated the morphology, optoelectrical properties and energy level of KPS-doped hole transport layer (HTL). The results indicate that the incorporation of KPS could not only oxidize spiro-OMeTAD efficiently, but also suppress ion migration by passivating the defect states at the perovskite surface. Accordingly, the KPS-modified PSC with a champion PCE of 20.23% delivered a stabilized output efficiency of 19.59%, while the control device exhibited an inferior PCE of 18.29% with a stabilized power output of 17.51%. More importantly, the devices employed KPS-doped spiro-OMeTAD exhibited less hysteresis and superior long-term stability. Our study provides an insight for HTL engineering by using a low-cost inorganic oxidant for highly efficient and stable PSCs.