Cai Huimin, Zhu Qiliang, Pan Tianchen, Wu Lunbi, Gu Xin, Duan Chenghao, Xiong Liangbin, Wu Jiaying, Liu Sha, Yu Liyang, Li Ruipeng, Yan Keyou, Ma Ruijie, Liu Shengjian, Jia Tao, Li Gang
School of Optoelectronic Engineering, Guangdong Polytechnic Normal University, Guangzhou, 510665, P.R. China.
School of Environment and Energy, State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, 510000, P.R. China.
Angew Chem Int Ed Engl. 2025 Jun 2;64(23):e202502478. doi: 10.1002/anie.202502478. Epub 2025 Apr 11.
Inorganic perovskites are known for their excellent photothermal stability; however, the photothermal stability of all-inorganic n-i-p perovskite solar cells (PSCs) is compromised due to ion diffusion and free radical-induced degradation caused by the use of doped spiro-OMeTAD hole transport materials (HTMs). In this study, two isomeric donor-acceptor-donor (D-A-D) type small molecules, namely HBT and HiBT, were developed and used as dopant-free HTMs, using 2,1,3-benzothiadiazole or benzo[d][1,2,3]thiadiazole as acceptor moieties. The HiBT molecule, with its symmetry-breaking features, exhibits a large dipole moment, enhanced coordination-active sites, and a well-aligned energy level structure, all of which contribute to passivating perovskite surface defects and improving free charge separation. As a result, inorganic CsPbI PSCs with HiBT HTM achieved an impressive power conversion efficiency (PCE) of 20.58%, the highest reported for dopant-free HTM-based inorganic PSCs. Moreover, the enhanced hydrophobic properties of HiBT molecules, coupled with their ability to passivate perovskite surface defects, contribute to significantly improved device stability. The unencapsulated devices based on HiBT HTM retained over 83% and 80% of their initial efficiency after being stored at 85 °C for 50 days and undergoing maximum power point (MPP) tracking at 85 °C for 1100 h, respectively. These results highlight that the symmetry-breaking strategy is an exceptionally effective approach for designing efficient, dopant-free small molecule HTMs, significantly contributing to both the high efficiency and enhanced stability of all-inorganic PSCs.
无机钙钛矿以其优异的光热稳定性而闻名；然而，由于使用掺杂的螺环-OMeTAD空穴传输材料（HTM）导致离子扩散和自由基诱导的降解，全无机n-i-p钙钛矿太阳能电池（PSC）的光热稳定性受到影响。在本研究中，开发了两种异构体供体-受体-供体（D-A-D）型小分子，即HBT和HiBT，并将其用作无掺杂HTM，使用2,1,3-苯并噻二唑或苯并[d][1,2,3]噻二唑作为受体部分。具有对称性破缺特征的HiBT分子表现出大的偶极矩、增强的配位活性位点和良好排列的能级结构，所有这些都有助于钝化钙钛矿表面缺陷并改善自由电荷分离。结果，采用HiBT HTM的无机CsPbI PSCs实现了令人印象深刻的20.58%的功率转换效率（PCE），这是基于无掺杂HTM的无机PSC所报道的最高效率。此外，HiBT分子增强的疏水性及其钝化钙钛矿表面缺陷的能力有助于显著提高器件稳定性。基于HiBT HTM的未封装器件在85°C下储存50天和在85°C下进行最大功率点（MPP）跟踪1100小时后，分别保留了其初始效率的83%以上和80%以上。这些结果突出表明，对称性破缺策略是设计高效、无掺杂小分子HTM的一种极其有效的方法，对全无机PSC的高效率和增强稳定性都有显著贡献。
