Spiro-Phenylpyrazole-9,9′-Thioxanthene Analogues as Hole-Transporting Materials for Efficient Planar Perovskite Solar Cells

3 years ago

Spiro-Phenylpyrazole-9,9′-Thioxanthene Analogues as Hole-Transporting Materials for Efficient Planar Perovskite Solar Cells

Yang Wang, Zonglong Zhu, Chu-Chen Chueh, Alex K.-Y. Jen, Yun Chi

Perovskite solar cells have emerged as a promising technique for low-cost, light weight, and highly efficient photovoltaics. However, they still largely rely on 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (Spiro-OMeTAD) to serve as hole-transporting materials (HTMs). Here, a series of HTMs with small molecular weight is designed, which are constructed on a spiro core involving phenylpyrazole and a second heteroaromatics, i.e., xanthene (O atom), thioxanthene (S atom), and acridine (N atom). Through varying from phenylpyrazole substituted xanthene (PPyra-XA), thioxanthene (PPyra-TXA), to acridine (PPyra-ACD), their optical and electrochemical properties, hole mobilities, and the photovoltaic performance are optimized. As a consequence, PPyra-TXA based device exhibits the highest power conversion efficiency (PCE) of 18.06%, outperforming that of Spiro-OMeTAD (16.15%), which could be attributed to the enhancement of hole mobility exerted by the thioxanthene. In addition, the dopant-free device shows PCE of 11.7%. These results open a new direction for designing spiro-HTMs by simple modification of chemical structures. Perovskite solar cells bearing spiro-phenylpyrazole-9,9′-thioxanthene exhibit power conversion efficiency of 18.06%, outperforming that of Spiro-OMeTAD (16.15%), which could be attributed to the enhancement of hole mobility exerted by the thioxanthene.

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

DOI: 10.1002/aenm.201700823