Recently,cesium bismuth halide perovskites have emerged as potential substitutes to their counterparts,cesium lead halide perovskites,owing to their low toxicity.However,the photophysics of cesium-bismuth halides nano...Recently,cesium bismuth halide perovskites have emerged as potential substitutes to their counterparts,cesium lead halide perovskites,owing to their low toxicity.However,the photophysics of cesium-bismuth halides nanocrystals(NCs)have not yet been fully rationalized because their structures remain highly debated.The ultraviolet-visible(UV-vis)absorption along with other photophysical properties such as the nature and lifetime of the excited states vary considerably across the previous reports.Here,we successfully synthesize pure Cs_(3)BiBr_(6)and Cs_(3)Bi_(2)Br_(9)NCs via a modified hot-injection method,where the structure can be easily controlled by tuning the reaction temperature.The UV-vis absorption spectrum of the pure Cs_(3)Bi_(2)Br_(9)NCs features two characteristic peaks originating from the absorption of the first exciton and second exciton,respectively,which ultimately clarifies the debate in the previous reports.Using femtosecond transient absorption spectroscopy,we systematically investigate the excited state dynamics of the Cs_(3)Bi_(2)Br_(9)NCs and reveal that the photoexcited carriers undergo a self-trapping process within 3 ps after excitation.More intriguingly,the Cs_(3)Bi_(2)Br_(9)NCs prepared by this method show much better photostability than those prepared by the ligand-assisted reprecipitation process.Photodetectors based on these Cs_(3)Bi_(2)Br_(9)NCs show a sensitive light response,demonstrating the definite potential for breakthrough optoelectronic applications.展开更多
环保型CuInSe_(2)量子点具有高消光系数和宽光谱吸收范围,在光电化学催化应用中展现了良好的发展前景.然而,CuInSe_(2)量子点较低的载流子分离能力和严重的界面电荷复合降低了其光电化学性能,制约了其应用.因此,我们设计并合成了具有Ⅱ...环保型CuInSe_(2)量子点具有高消光系数和宽光谱吸收范围,在光电化学催化应用中展现了良好的发展前景.然而,CuInSe_(2)量子点较低的载流子分离能力和严重的界面电荷复合降低了其光电化学性能,制约了其应用.因此,我们设计并合成了具有Ⅱ型能带排列的CuInSe_(2)/CuInS_(2)核/壳结构量子点,以促进载流子分离、减少界面缺陷;进一步通过调节In/Cu前驱体的摩尔比,产生铜空位.光物理性质研究表明,导带电子-铜空位捕获的空穴之间的辐射复合成为主要的复合方式,有效延长了载流子寿命,促进了载流子分离.因此,基于富铜空位的CuInSe_(2)/CuInS_(2)核壳量子点的光阳极获得了~8.0 mA cm^(-2)的最大饱和光电流密度,该性能是当前报道的CISe基量子点光电化学电池中的最高值之一.本工作提供了一种通过表面或内在缺陷的调控来促进光电化学应用中的电荷载流子分离和传输的有效方法.展开更多
基金supported by the National Key Research and Development Program of China(2020YFA0309300)the Natural Science Foundation of Tianjin(20JCZDJC00560 and 20JCJQJC00210)+2 种基金the National Natural Science Foundation of China(NSFC,11974191 and 12127803)the 111 Project(B07013)the“Fundamental Research Funds for the Central Universities”,Nankai University(91923139,63213040,C029211101,C02922101,and ZB22000104)。
文摘Recently,cesium bismuth halide perovskites have emerged as potential substitutes to their counterparts,cesium lead halide perovskites,owing to their low toxicity.However,the photophysics of cesium-bismuth halides nanocrystals(NCs)have not yet been fully rationalized because their structures remain highly debated.The ultraviolet-visible(UV-vis)absorption along with other photophysical properties such as the nature and lifetime of the excited states vary considerably across the previous reports.Here,we successfully synthesize pure Cs_(3)BiBr_(6)and Cs_(3)Bi_(2)Br_(9)NCs via a modified hot-injection method,where the structure can be easily controlled by tuning the reaction temperature.The UV-vis absorption spectrum of the pure Cs_(3)Bi_(2)Br_(9)NCs features two characteristic peaks originating from the absorption of the first exciton and second exciton,respectively,which ultimately clarifies the debate in the previous reports.Using femtosecond transient absorption spectroscopy,we systematically investigate the excited state dynamics of the Cs_(3)Bi_(2)Br_(9)NCs and reveal that the photoexcited carriers undergo a self-trapping process within 3 ps after excitation.More intriguingly,the Cs_(3)Bi_(2)Br_(9)NCs prepared by this method show much better photostability than those prepared by the ligand-assisted reprecipitation process.Photodetectors based on these Cs_(3)Bi_(2)Br_(9)NCs show a sensitive light response,demonstrating the definite potential for breakthrough optoelectronic applications.
基金supported by the National Natural Science Foundation of China (52011530123,52272134,and 51902019)Beijing Natural Science Foundation (2222061 and 2232082)+4 种基金the IndustryUniversity-Research Cooperative Education of Ministry of Education (2205064205258 and 220606429170400)Shandong Weiqiao Pioneering Group Company Limited (BINTECH-KJZX-20220831-09 and BINTECHKJZX-20220831-29)the support from Swedish Research Council (2021-05319)Danish Villum Foundation Experiment Grant (50350)Swedish Foundation for International Cooperation in Research and Higher Education (F2020/1618)。
文摘环保型CuInSe_(2)量子点具有高消光系数和宽光谱吸收范围,在光电化学催化应用中展现了良好的发展前景.然而,CuInSe_(2)量子点较低的载流子分离能力和严重的界面电荷复合降低了其光电化学性能,制约了其应用.因此,我们设计并合成了具有Ⅱ型能带排列的CuInSe_(2)/CuInS_(2)核/壳结构量子点,以促进载流子分离、减少界面缺陷;进一步通过调节In/Cu前驱体的摩尔比,产生铜空位.光物理性质研究表明,导带电子-铜空位捕获的空穴之间的辐射复合成为主要的复合方式,有效延长了载流子寿命,促进了载流子分离.因此,基于富铜空位的CuInSe_(2)/CuInS_(2)核壳量子点的光阳极获得了~8.0 mA cm^(-2)的最大饱和光电流密度,该性能是当前报道的CISe基量子点光电化学电池中的最高值之一.本工作提供了一种通过表面或内在缺陷的调控来促进光电化学应用中的电荷载流子分离和传输的有效方法.
