Kim, G.等人采用溶液法合成出一种无机-有机复合的空穴传输层，即WO3和spiro-OMeTAD。该复合层的空穴提取能力强和空穴迁移率高，基于该复合结构的电池效率高达21.44%，稳定性也得到大幅提升。
Kim, G.-W., Kang, G., Choi, K., Choi, H. & Park, T. Solution Processable Inorganic–Organic Double-Layered Hole Transport Layer for Highly Stable Planar Perovskite Solar Cells. Adv. Energy Mater. Doi:10.1002/aenm.201801386.
https://doi.org/10.1002/aenm.201801386.
