Temperature and composition dependence of photoluminescence dynamics in CdS xSe 1-x (0 ≤ x ≤ 1) nanobelts

Abstract

CdS xSe 1-x nanobelts with uniform and controllable composition are successfully fabricated by a one-step vapor-liquid-solid process. Temperature-dependent steady and time-resolved transient photoluminescence (PL) are studied for the obtained CdS xSe 1-x nanobelts as well as pure CdS and CdSe nanobelts prepared in same method. For all samples, both band edge and surface state emission are found to contribute to the observed PL spectra. However, the emission originated from surface state is quite weak for CdS xSe 1-x nanobelts as compared to CdS and CdSe. The reduced surface state emission in CdS xSe 1-x nanobelts is ascribed to exciton localization due to random potential fluctuations. This attribution is further confirmed by the time-decay PL profiles where a very fast process of exciton transfer from interior to surface of nanobelts, observed in CdS and CdSe nanobelts, is absent for CdS xSe 1-x nanobelts. These observations reveal that the surface effect of CdS xSe 1-x nanobelts is less significant than that in CdS and CdSe nanobelts, which consequently leads to enhanced band-edge emission in CdS xSe 1-x nanobelts. © 2012 American Institute of Physics.