Dopant-Free Hole-Transport Materials Based on Methoxytriphenylamine-Substituted Indacenodithienothiophene for Solution-Processed Perovskite Solar Cells

5 years ago

Dopant-Free Hole-Transport Materials Based on Methoxytriphenylamine-Substituted Indacenodithienothiophene for Solution-Processed Perovskite Solar Cells

Fang Yao, Guojia Fang, Zhiliang Chen, Zhi-Kuan Chen, Yulong Wang, Xiaolu Zheng, Zong-Xiang Xu, Qi Zhang, Wei Huang, Xiaoyuan Liu

Solution-processed hole transporting materials (HTMs) that are dopant-free show promise for use in low-cost, high-performance perovskite solar cells (PSCs). The highest-efficiency PSCs use organic HTMs, many of which have low mobilities and therefore require doping, which lowers the device stability. Additionally, these materials are not easily scaled because they often require complicated synthesis. Two new HTMs (IDT–TPA and IDTT–TPA) were synthesized, which contained either an extended fused-ring indacenodithiophene (IDT) or indacenodithienothiophene (IDTT) core and strong electron-donating methoxytriphenylamine (TPA) groups as the end-capping units. The extended conjugation in the backbone of IDTT–TPA resulted in stronger π–π interactions (3.321 Å) and a higher hole mobility of 6.46×10−4 cm2 V−1 s−1 when compared with that of IDT–TPA (9.53×10−5 cm2 V−1 s−1). A dopant-free, planar PSC that contained IDTT–TPA was fabricated and exhibited a high power conversion efficiency (PCE) of 15.7 %. This cell exhibited a higher PCE and less hysteresis than devices that contained IDT–TPA. Anti-doping: A power conversion efficiency of 15.7 % was achieved with a perovskite solar cell that incorporated dopant-free methoxytriphenylamine-substituted indacenodithienothiophene (IDTT–TPA) as hole-transport material. IDTT–TPA exhibited a higher hole mobility than methoxytriphenylamine-substituted indacenodithiophene (IDT–TPA) because of its extended fused ring and rigid coplanar structure, which are beneficial for π-electron delocalization, preventing rotational disorder, and increasing π–π interactions.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/cssc.201700197