Accurately Stoichiometric Regulating Oxidation States in Hole Transporting Material to Enhance the Hole Mobility of Perovskite Solar Cells

作者：Chen, Cheng; Liu, Sizhou; Li, Zhipeng; Wang, Fangfang^*; Xu, Wenxin; Ma, Hongzhuang; Zhang, Shitong; Wang, Lingling; Gu, Cheng; Pang, Shuping; Huang, Wei; Qin, Tianshi^*

来源：Solar RRL, 2020, 4(6): 2000127.

DOI：10.1002/solr.202000127

• hole mobilities
• hole transport materials
• perovskite solar cells
• phenothiazine
• radical cations

In traditional n-i-p-type perovskite solar cells (PSCs), most hole transporting materials (HTMs) rely on an uncontrolled oxidative process using Li salt and Co (III) complex to achieve sufficient hole mobilities. Herein, a stabilized oxidized phenothiazine-based HTM (OPTZ) synthesized from its neutral form (NPTZ) through a photoredox reaction is demonstrated. This controllable and stable oxidation state is mainly derived from the planar structure and pi conjugation of phenothiazine core in OPTZ. The energy gap between the singly occupied molecular orbital (SOMO) of OPTZ and highest occupied molecular orbital (HOMO) of NPTZ suitably promotes hole hopping in hole transporting layers. Using an optimized ratio of OPTZ as the dopant in NPTZ, the hole transporting mobility is effectively enhanced due to an intra- and intermolecular charge transfer process, resulting in an enhancement in the fill factor of the PSCs. Herein, a new strategy to obtain stabilized oxidized HTMs, which deliver significantly enhanced hole mobilities of HTMs in PSCs, is provided.

• 单位
  西北工业大学; 5; 中国科学院青岛生物能源与过程研究所; 吉林大学