期刊
ACS APPLIED ENERGY MATERIALS
卷 3, 期 12, 页码 12525-12531出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsaem.0c02478
关键词
single charged; double charged; semiconductor nanocrystals; spectroelectrochemistry; transient absorption spectroscopy; polaron; tetron; Auger decay; solar cells; optoelectronics
资金
- Independent Research Fund Denmark, Sapere Aude Starting Grant [7026-00037A]
- Swedish Research Council VR Starting Grant [2017-05337]
- China Scholarship Council (CSC) [201806460021]
- Vinnova [2017-05337] Funding Source: Vinnova
- Swedish Research Council [2017-05337] Funding Source: Swedish Research Council
Fulfilling the potential of colloidal semiconductor quantum dots (QDs) in electrically driven applications remains a challenge largely since operation of such devices involves charged QDs with drastically different photophysical properties compared to their well-studied neutral counterparts. In this work, the full picture of excited state dynamics in charged CdSe QDs at various time scales has been revealed via transient absorption spectroscopy combined with electrochemistry as a direct manipulation tool to control the negative charging of CdSe QDs. In trions, excited states of single charged QDs, the additional electron in the conduction band speeds up the hot electron cooling by enhanced electron-electron scattering followed by charge redistribution and polaron formation in a picosecond time scale. The trions are finally decayed by the Auger process in a 500 ps time scale. Double charging in QDs, on the other hand, decelerates the polaron formation process while accelerates the following Auger decay. Our work demonstrates the potential of photoelectrochemistry as a platform for ultrafast spectroscopy of charged species and paves the way for further studies to develop comprehensive knowledge of the photophysical processes in charged QDs more than the well-known Auger decay, facilitating their use in future optoelectronic applications.
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