Cation‐Exchange Synthesis of Highly Monodisperse PbS Quantum Dots from ZnS Nanorods for Efficient Infrared Solar Cells

• Published in: Advanced functional materials 2020-01, Vol.30 (4), p.n/a
• Main Authors: Xia, Yong, Liu, Sisi, Wang, Kang, Yang, Xiaokun, Lian, Linyuan, Zhang, Zhiming, He, Jungang, Liang, Guijie, Wang, Song, Tan, Manlin, Song, Haisheng, Zhang, Daoli, Gao, Jianbo, Tang, Jiang, Beard, Matthew C., Zhang, Jianbing
• Format: Article
• Language: English
• Subjects: cation exchange; Cation exchanging; Control stability; Efficiency; Energy gap; Lead sulfides; Materials science; Nanorods; PbS; Perovskites; Photovoltaic cells; Quantum dots; Solar cells; Solar energy; Superlattices; Surface stability; Synthesis; Zinc sulfide
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201907379

Infrared solar cells that utilize low‐bandgap colloidal quantum dots (QDs) are promising devices to enhance the utilization of solar energy by expanding the harvested photons of common photovoltaics into the infrared region. However, the present synthesis of PbS QDs cannot produce highly efficient infrared solar cells. Here, a general synthesis is developed for low‐bandgap PbS QDs (0.65–1 eV) via cation exchange from ZnS nanorods (NRs). First, ZnS NRs are converted to superlattices with segregated PbS domains within each rod. Then, sulfur precursors are released via the dissolution of the ZnS NRs during the cation exchange, which promotes size focusing of PbS QDs. PbS QDs synthesized through this new method have the advantages of high monodispersity, ease‐of‐size control, in situ passivation of chloride, high stability, and a “clean” surface. Infrared solar cells based on these PbS QDs with different bandgaps are fabricated, using conventional ligand exchange and device structure. All of the devices produced in this manner show excellent performance, showcasing the high quality of the PbS QDs. The highest performance of infrared solar cells is achieved using ≈0.95 eV PbS QDs, exhibiting an efficiency of 10.0% under AM 1.5 solar illumination, a perovskite‐filtered efficiency of 4.2%, and a silicon‐filtered efficiency of 1.1%. A new synthesis of large PbS quantum dots (QDs) via cation‐exchange from ZnS nanorods (NRs) is developed, which produces PbS QDs with extremely high monodispersity. Infrared solar cells based on these PbS QDs with different bandgaps show excellent performance. The best device exhibits an efficiency of 10.0% under AM 1.5 solar illumination, perovskite‐filtered efficiency of 4.2%, and silicon‐filtered efficiency of 1.1%.