A dithieno[3,2-:2′,3′-]pyrrole-cored four-arm hole transporting material for over 19% efficiency dopant-free perovskite solar cells

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2019, Vol.7 (31), p.9455-9459
• Main Authors: Dong, Zihao, Yin, Xinxing, Ali, Amjad, Zhou, Jie, Bista, Sandip Singh, Chen, Cong, Yan, Yanfa, Tang, Weihua
• Format: Article
• Language: English
• Subjects: Dopants; Efficiency; Energy conversion efficiency; Glass transition temperature; Hole mobility; Ionization potentials; Maximum power; Perovskites; Photovoltaic cells; Solar cells; Thermal stability; Transporting
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/c9tc03111a

Dopant-free hole transporting materials (HTMs) have been in the limelight in the quest for stable perovskite solar cells (PVSCs). Herein, we report a novel dopant-free HTM featuring a dithieno[3,2- b :2′,3′- d ]pyrrole core flanked with two-fold triphenylamine arm substituted thiophene bridges. This star-shaped molecule shows a suitable ionization potential (5.13 eV), good thermal stability (high glass-transition temperature of 120.3 °C) and a high hole mobility (6.50 × 10 −5 cm 2 V −1 s −1 ). The molecule is more hydrophobic than reference spiro-OMeTAD in a film. By capping our dopant-free HTM on the perovskite layer, the fabricated n-i-p device can achieve a maximum power conversion efficiency of 19.42%, which is comparable to the device based on doped spiro-OMeTAD (19.59%). This star-shaped dithieno[3,2- b :2′,3′- d ]pyrrole based molecule is thus a promising candidate HTM for upscaling the commercial manufacture of PVSCs. A dithieno[3,2- b :2′,3′- d ]pyrrole-cored four-arm hole transporting material has been designed to realize over 19% efficiency dopant-free perovskite solar cells.