Organic-inorganic 3D halide perovskite materials recently have become one of the major players of hybrid semiconductors for photovoltaic and optoelectronic applications.The diffusion length of charge carriers is one o...Organic-inorganic 3D halide perovskite materials recently have become one of the major players of hybrid semiconductors for photovoltaic and optoelectronic applications.The diffusion length of charge carriers is one of the critical parameters for justifying photovoltaic applications of materials.In this work,we propose a realistic kinetic model in order to fully understand carrier relaxation rate of photoexcited organic perovskites with a negligible exciton formation in photoluminescence lifetime measurements.We find that the extraction of carrier relaxation rate has to be made from multiple fluence-dependent photoluminescence lifetime measurements with global fittings,instead of a traditional single fluence lifetime measurement.To demonstrate the validity of the model,two kinds of p-doped CH3NH3PbI3 single crystals were grown up by intentionally increasing defects.Global fittings of the kinetic model to the two kinds of single crystals yield doping density,trap density,and recombination constants.Our methodology provides a self-contained approach to determine diffusion lengths of organic 3D halide perovskite materials.展开更多
Nanoparticles of refractory compounds represent a class of stable materials showing a great promise to support localized surface plasmon resonances(LSPRs)in both visible and near infrared(NIR)spectral regions.It is st...Nanoparticles of refractory compounds represent a class of stable materials showing a great promise to support localized surface plasmon resonances(LSPRs)in both visible and near infrared(NIR)spectral regions.It is still challenging to rationally tune the LSPR band because of the difficulty to control the density of charge carriers in individual refractory nanoparticles and maintain the dispersity of nanoparticles in the processes of synthesis and applications.In this work,controlled chemical transformation of titanium dioxide(TiO_(2))nanoparticles encapsulated with mesoporous silica(SiO_(2))shells to titanium nitride(TiN)via nitridation reaction at elevated temperatures is developed to tune the density of free electrons in the resulting titanium-oxide-nitride(TiO_(x)N_(y))nanoparticles.Such tunability enables a flexibility to support LSPR-based optical absorption in the synthesized TiO_(x)N_(y)@SiO_(2) core-shell nanoparticles across both the visible and NIR regions.The silica shells play a crucial role in preventing the sintering of TiO_(x)N_(y) nanoparticles in the nitridation reaction and maintaining the stability of TiOxNy nanoparticles in applications.The LSPR-based broadband absorption of light in the TiO_(x)N_(y)@SiO_(2) nanoparticles exhibits strong photothermal effect with photo-to-thermal conversion efficiency as high as〜76%.展开更多
基金supported by the National Natural Science Foundation of China (No.21773221 and No.21827804)the National Key R&D Program of China (2017YFA0303502)Fundamental Research Funds for the Central Universities of China(WK2340000078).
文摘Organic-inorganic 3D halide perovskite materials recently have become one of the major players of hybrid semiconductors for photovoltaic and optoelectronic applications.The diffusion length of charge carriers is one of the critical parameters for justifying photovoltaic applications of materials.In this work,we propose a realistic kinetic model in order to fully understand carrier relaxation rate of photoexcited organic perovskites with a negligible exciton formation in photoluminescence lifetime measurements.We find that the extraction of carrier relaxation rate has to be made from multiple fluence-dependent photoluminescence lifetime measurements with global fittings,instead of a traditional single fluence lifetime measurement.To demonstrate the validity of the model,two kinds of p-doped CH3NH3PbI3 single crystals were grown up by intentionally increasing defects.Global fittings of the kinetic model to the two kinds of single crystals yield doping density,trap density,and recombination constants.Our methodology provides a self-contained approach to determine diffusion lengths of organic 3D halide perovskite materials.
基金funded by the department of the Army Basic Research Program through the Edgewood Chemical and Biological Center,U.S.Army Research Office(No.W911NF-15-2-0052).
文摘Nanoparticles of refractory compounds represent a class of stable materials showing a great promise to support localized surface plasmon resonances(LSPRs)in both visible and near infrared(NIR)spectral regions.It is still challenging to rationally tune the LSPR band because of the difficulty to control the density of charge carriers in individual refractory nanoparticles and maintain the dispersity of nanoparticles in the processes of synthesis and applications.In this work,controlled chemical transformation of titanium dioxide(TiO_(2))nanoparticles encapsulated with mesoporous silica(SiO_(2))shells to titanium nitride(TiN)via nitridation reaction at elevated temperatures is developed to tune the density of free electrons in the resulting titanium-oxide-nitride(TiO_(x)N_(y))nanoparticles.Such tunability enables a flexibility to support LSPR-based optical absorption in the synthesized TiO_(x)N_(y)@SiO_(2) core-shell nanoparticles across both the visible and NIR regions.The silica shells play a crucial role in preventing the sintering of TiO_(x)N_(y) nanoparticles in the nitridation reaction and maintaining the stability of TiOxNy nanoparticles in applications.The LSPR-based broadband absorption of light in the TiO_(x)N_(y)@SiO_(2) nanoparticles exhibits strong photothermal effect with photo-to-thermal conversion efficiency as high as〜76%.
