Perovskite hybrid solar cells with a fullerene derivative electron extraction layer
Perovskite hybrid solar cells (pero-HSCs) have attracted great attention in the past 7 years. Boosting the efficiency of pero-HSCs is still one ongoing direction. In this study, we report efficient pero-HSCs with [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) as an electron extraction layer (EEL), where the PC61BM EEL is processed from chlorobenzene mixed with pyridine solution (PC61BM-Py EEL) rather than from pure chlorobenzene solution (PC61BM EEL). It is found that the PC61BM-Py EEL exhibits dramatically enhanced electrical conductivity and has a smoother and denser thin film, as compared with that of the PC61BM EEL. Moreover, transient photovoltage and transient photocurrent measurements demonstrate that a long charge carrier lifetime and a short charge extraction time are observed for the pero-HSCs incorporated with the PC61BM-Py EEL, as compared with that with the PC61BM EEL, indicating that the charge carrier recombination is significantly reduced. As a result, more than 21.6% enhanced efficiency is observed for the pero-HSCs incorporated with the PC61BM-Py EEL. Our finding provides a simple but an effective way to significantly boost the efficiency of pero-HSCs.