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Unravelling the Role of Surface Traps on Carrier Relaxation and Transfer Dynamics in Ultrasmall Semiconductor Nanocrystals
journal contribution
posted on 2018-08-27, 00:00 authored by Supriya Ghosh, Dushyant Kushavah, Suman Kalyan PalCharge
carrier trapping by the surface defects of colloidal semiconductor
nanocrystal (NC) is a ubiquitous process which limits the performance
of NC-based photovoltaic and photocatalytic devices. Although several
empirical approaches led to the enhancement of device efficiency via
passivation of trap states, a systematic and unified description of
trapping mechanism remains obscure. In this contribution, we present
a detailed experimental investigation of the carrier dynamics of CdSe
NCs with varying concentration of surface traps by means of time-resolved
photoluminescence (PL) and absorption. Our study reveals that the
rate of carrier cooling becomes faster as trap density increases because
of the increased hot carrier trapping. A comparative dynamical study
is also presented to demonstrate how trap states influence electron
injection process. This enhanced understanding of the role of trap
sates on charge carrier dynamics can provide valuable insight toward
the rational development of more efficient NC-based optoelectronic
devices.
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Carrier Relaxationtrap density increasescarrier coolingsemiconductor nanocrystaltrap satesCdSe NCssurface trapsphotocatalytic devicesUltrasmall Semiconductor Nanocrystals Charge carrierdevice efficiencyPLTransfer Dynamicssurface defectstrap states influence electron injection processcarrier dynamicstrap statestime-resolved photoluminescenceNC-based photovoltaicNC-based optoelectronic devicesSurface Trapscharge carrier dynamics
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