摘要
Cesium lead iodide(CsPbI_(3))is a promising photo-absorber for perovskite photovoltaics due to its high thermal stability and relatively small bandgap.However,there are many defects in solution processed polycrystalline CsPbI_(3)films especially at the grain boundaries(GBs),which limit the power conversion efficiency(PCE)of CsPbI_(3)solar cells.In this work,we introduced CsPbBr_(3)quantum dots(QDs)on top of the CsPbI_(3)film to passivate the defects.As CsPbBr_(3)QDs have a small size and a similar crystal structure as the CsPbI_(3),they are excellent modifiers to fill in the GBs and heal the defects.Moreover,we find there is an anion exchange reaction between the CsPbBr_(3)QDs and CsPbI_(3)films,which is evidenced by photoluminescence spectra and grazing incidence X-ray diffraction patterns.The QDs treated films show enhanced carrier lifetime and reduced defect density.Additionally,the ligands on CsPbBr_(3)QDs increase the hydrophobicity of the films.As a result,the QDs treated CsPbI_(3)solar cells prepared at high temperature obtain PCEs exceeding 16%with high stability.
基金
supported by the National Key Research and Development Program of China(No.2018YFB1502003 and 2019YFE0123400)
the Tianjin Distinguished Young Scholars Fund(No.20JCJQJC00260)
the Chinese Thousand Talents Program for Young Professionals.
