Terahertz Spectroscopic Probe of Hot Electron and Hole Transfer from Colloidal CsPbBr 3 Perovskite Nanocrystals

• Published in: Nano letters Vol. 17; no. 9; pp. 5402 - 5407
• Main Authors: Sarkar, Sohini, Ravi, Vikash Kumar, Banerjee, Sneha, Yettapu, Gurivi Reddy, Markad, Ganesh B, Nag, Angshuman, Mandal, Pankaj
• Format: Journal Article
• Language: English
• Published: United States 13-09-2017
• Subjects: electron and hole transfer; Terahertz spectroscopy; CsPbBr3 nanocrystals; hot carrier transfer
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.7b02003

Colloidal all inorganic CsPbX
(X = Cl, Br, I) nanocrystals (NCs) have emerged to be an excellent material for applications in light emission, photovoltaics, and photocatalysis. Efficient interfacial transfer of photogenerated electrons and holes are essential for a good photovoltaic and photocatalytic material. Using time-resolved terahertz spectroscopy, we have measured the kinetics of photogenerated electron and hole transfer processes in CsPbBr
NCs in the presence of benzoquinone and phenothiazine molecules as electron and hole acceptors, respectively. Efficient hot electron/hole transfer with a sub-300 fs time scale is the major channel of carrier transfer thus overcomes the problem related to Auger recombination. A secondary transfer of thermalized carriers also takes place with time scales of 20-50 ps for electrons and 137-166 ps for holes. This work suggests that suitable interfaces of CsPbX
NCs with electron and hole transport layers would harvest hot carriers, increasing the photovoltaic and photocatalytic efficiencies.