Photophysics of size-selected InP nanocrystals: exciton recombination kinetics

2019-10-11 00:33:39

state size quantum dependent recombination

责任者: Kim, S.-H.;Wolters, R.H.;Heath, J.R. 单位: Dept. of Chem. & Biochem., California Univ., Los Angeles, CA, USA 来源出处: Journal of Chemical Physics(J. Chem. Phys. (USA)),1996/11/08,105(18):7957-63 摘要: We report here on the size-dependent kinetics of exciton recombination in a III-V quantum dot system, InP. The measurements reported include various frequency dependent quantum yields as a function of temperature, frequency dependent luminescence decay curves, and time-gated emission spectra. This data is fit to a three-state quantum model which has been previously utilized to explain photophysical phenomena in II-VI quantum dots. The initial photoexcitation is assumed to place an electron in a (delocalized) bulk conduction band state. Activation barriers for trapping and detrapping of the electron to surface states, as well as activation barriers for surface-state radiationless relaxation processes are measured as a function of particle size. The energy barrier to detrapping is found to be the major factor limiting room temperature band-edge luminescence. This barrier increases with decreasing particle size. For 30 Å particles, this barrier is found to be greater than 6 kT/mol-a barrier which is more than an order of magnitude larger than that previously found for 32 Å CdS nanocrystals 关键词: conduction bands;excitons;III-V semiconductors;indium compounds;particle size;photoexcitation;photoluminescence;semiconductor quantum dots;surface recombination;time resolved spectra;photophysics;size-selected InP nanocrystals;exciton recombination kinetics;size-dependent kinetics;exciton recombination;III-V quantum dot system;frequency dependent quantum yields;frequency dependent luminescence decay curves;time-gated emission spectra;three-state quantum model;photophysical phenomena;II-VI quantum dots;initial photoexcitation;delocalized bulk conduction band state;activation barriers;trapping;detrapping;surface-state radiationless relaxation processes;CdS nanocrystals;time resolved photoluminescence spectra;30 A;0 to 300 K;2.5 to 1.5 eV;InP