Using time-dependent terahertz spectroscopy, we investigate the role of mixed-cation and mixed-halide on the ultrafast photoconductivity dynamics of two different methylammonium(MA) lead-iodide perovskite thin films. ...Using time-dependent terahertz spectroscopy, we investigate the role of mixed-cation and mixed-halide on the ultrafast photoconductivity dynamics of two different methylammonium(MA) lead-iodide perovskite thin films. It is found that the dynamics of conductivity after photoexcitation reveals significant correlation on the microscopy crystalline features of the samples. Our results show that mixed-cation and lead mixed-halide affect the charge carrier dynamics of the lead-iodide perovskites. In the(5-AVA)_(0.05)(MA)_(0.95) PbI_(2.95) Cl_(0.05)/spiro thin film, we observe a much weaker saturation trend of the initial photoconductivity with high excitation fluence, which is attributed to the combined effect of sequential charge carrier generation, transfer, cooling and polaron formation.展开更多
Perovskite quantum dots(QDs) confined within solid matrices via calcination methods exhibit superior environmental stability compared to colloidal perovskite QDs.However;matrix-confined perovskite QDs generally displa...Perovskite quantum dots(QDs) confined within solid matrices via calcination methods exhibit superior environmental stability compared to colloidal perovskite QDs.However;matrix-confined perovskite QDs generally display lower photoluminescence quantum yield(PLQY)than their colloidal counterparts;especially in the case of blue-emitting mixed-halide CsPb(Cl/Br)_(3)QDs.Here;we identify residual tensile stress;originating from the mismatch in thermal expansion coefficients between the perovskite and the matrix;as a key factor responsible for the suppressed luminous efficiency in silica-confined CsPb(Cl/Br)_(3)QDs.Furthermore;we demonstrate that a simple hydrothermal treatment enables stress release in these silica-confined QDs;leading to a significant enhancement in their PLQY.The resulting stress-free silica-confined CsPb(Cl/Br)_(3)QDs exhibit record-high PLQYs among reported blue-emitting perovskite QDs synthesized via calcination methods;even approaching the PLQY of colloidal QDs.In addition;we find that stress release effectively suppresses both photoinduced halide segregation and thermal-induced emission quenching in these silica-confined CsPb(Cl/Br)_(3)QDs.This work provides a new perspective for achieving blue-emitting perovskite QDs with high PLQY and stability.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11604202,11674213,61735010 and 51603119the Young Eastern Scholar under Grant Nos QD2015020 and QD2016027+3 种基金the Shanghai Rising-Star Program under Grant No18QA1401700the ‘Chen Guang’ Project under Grant Nos 16CG45 and 16CG46the Shanghai Municipal Education Commissionthe Shanghai Education Development Foundation
文摘Using time-dependent terahertz spectroscopy, we investigate the role of mixed-cation and mixed-halide on the ultrafast photoconductivity dynamics of two different methylammonium(MA) lead-iodide perovskite thin films. It is found that the dynamics of conductivity after photoexcitation reveals significant correlation on the microscopy crystalline features of the samples. Our results show that mixed-cation and lead mixed-halide affect the charge carrier dynamics of the lead-iodide perovskites. In the(5-AVA)_(0.05)(MA)_(0.95) PbI_(2.95) Cl_(0.05)/spiro thin film, we observe a much weaker saturation trend of the initial photoconductivity with high excitation fluence, which is attributed to the combined effect of sequential charge carrier generation, transfer, cooling and polaron formation.
基金National Natural Science Foundation of China,Grant/Award Numbers:52072337,52102188Key Research and Development Program of Zhejiang Province,Grant/Award Number:2021C01030+4 种基金Young Elite Scientists Sponsorship Program by CAST,Grant/Award Number:YESS20210444Natural Science Foundation of Zhejiang Province,Grant/Award Number:LQ21F040005Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering,Grant/Award Number:2022SZ-TD004Basic Scientific Research Project of Wenzhou,Grant/Award Number:G20240039Major Scientific and Technological Innovation Project of Wenzhou,Grant/Award Number:ZG2023039。
文摘Perovskite quantum dots(QDs) confined within solid matrices via calcination methods exhibit superior environmental stability compared to colloidal perovskite QDs.However;matrix-confined perovskite QDs generally display lower photoluminescence quantum yield(PLQY)than their colloidal counterparts;especially in the case of blue-emitting mixed-halide CsPb(Cl/Br)_(3)QDs.Here;we identify residual tensile stress;originating from the mismatch in thermal expansion coefficients between the perovskite and the matrix;as a key factor responsible for the suppressed luminous efficiency in silica-confined CsPb(Cl/Br)_(3)QDs.Furthermore;we demonstrate that a simple hydrothermal treatment enables stress release in these silica-confined QDs;leading to a significant enhancement in their PLQY.The resulting stress-free silica-confined CsPb(Cl/Br)_(3)QDs exhibit record-high PLQYs among reported blue-emitting perovskite QDs synthesized via calcination methods;even approaching the PLQY of colloidal QDs.In addition;we find that stress release effectively suppresses both photoinduced halide segregation and thermal-induced emission quenching in these silica-confined CsPb(Cl/Br)_(3)QDs.This work provides a new perspective for achieving blue-emitting perovskite QDs with high PLQY and stability.
