Dopant-free and low-cost molecular "bee" hole-transporting materials for efficient and stable perovskite solar cells. Issue 44 (1st November 2017) - Liu, Xicheng
Abstract : TPD based molecular "bee" dopant-free HTMs for PSCs exhibit a PCE of 15.28% which is comparable to doped spiro -OMeTAD. Abstract : With the dramatic development of the power conversion efficiency (PCE) of perovskite solar cells (PSCs), the device lifetime has attracted extensive research interest and concern. To enhance device durability, developing dopant-free hole-transporting materials (HTMs) with a high performance is a promising strategy. Herein, three new HTMs with a N, N ′-diphenyl- N, N ′-di( m -tolyl)benzidine (TPD) core:TPD-4MeTPA, TPD-4MeOTPA andTPD-4EtCz are designed and synthesized, showing suitable energy levels and excellent film-formation properties. PCEs of 15.28% were achieved based on pristineTPD-4MeOTPA as the HTM, which is a little lower than that of the p-doped 2, 2′, 7, 7′-tetrakis-( N, N -di-4-methoxyphenylamino)-9, 9′-spirobifluorene ( spiro -OMeTAD)-based device (17.26%). Importantly, the devices based on the new HTMs show relatively improved stability compared to devices based on spiro -OMeTAD when aged under ambient air with 30% relative humidity in the dark.