Interface Manipulation In N-I-P-type Lead Halide Perovskite Solar Cells

Metal halide perovskite semiconductor(MHPs)materials have been a hot research topic in the past decade,especially in the field of photovoltaics.The maximum certified power conversion efficiency has reached 25.7%,which has attracted widespread attention in scientific research and industry community.A typical lead-halide perovskite solar cell mainly consists of an electron transporting layer,a hole transporting layer and a perovskite active layer between them;there are two main interfaces in the device:the perovskite/hole transporting layer interface and the electron transporting layer/perovskite interface.Properties of the interface are closely related to important technical indicators such as the open circuit voltage,photovoltaic performance and stability of the device.This project mainly studies the properties of perovskite/hole transporting layer interface in high-efficiency N-I-P-type lead halide perovskite solar cells.We manipulated the interface of perovskite by low-dimension perovskites and organic block copolymer,thus carrier dynamics process at the interface is effectively adjusted,enabling efficient and stable perovskite solar cells.This project can be divided into the following two parts:Part Ⅰ:Research on the interface manipulation by low-dimension perovskite materials and photovoltaic performance.We reconstructed the surface and grain boundaries of three-dimension perovskite by post-treatment with a secondary amine,namely dimethylamine hydroiodide.By forming low-dimension perovskite to passivate the defects of three-dimension perovskite,the non-radiative recombination of carriers at the interface is significantly reduced.In addition,the low-dimension/three-dimension perovskite heterojunction can be formed in the interior film through heat-induced infiltration,effectively promoting the extraction and transport of carriers.Finally,the highest efficiency of perovskite solar cells based on dimethylamine hydroiodide treatment reached 22.61%.Due to the protective effect of low-dimension perovskite on three-dimension perovskite,the device stability is significantly improved,and 80%of the initial efficiency can be maintained after aging in the air for 1000 h.Part Ⅱ:Research on the interface manipulation by block copolymer and photovoltaic performance.We designed a novel device architecture of polymer/perovskite hybrid bulk heterojunction by block copolymer PBDB-T-b-PTY6,creating an energy level cascade,thus enabling efficient energy transfer.In addition,the polymer provides a thin hydrophobic layer as a moisture barrier,preventing the intrusion of water molecules into the perovskite film.The resulting hybrid organic/perovskite solar cells exhibit efficiency over 22%with enhanced stability,which is among the highest reported efficiency for polymer/perovskite hybrid devices.The approach has been effectively extended to other MHPs with different chemical compositions(MAPbl3,CsPbI3),which has strong guidance for the fabrication of efficient and stable perovskite photovoltaic devices.Interface manipulation provides the possibility to obtain both efficient and stable perovskite solar cells.More suitable energy band alignment and good interfacial contact will not only facilitate the transport of carriers but also improve the stability of the device.In view of the diversification of current regulation methods,more efficient and stable perovskite solar cells can be realized through multiple interface manipulation in the future.