Abstract-Terahertz Spectroscopic Probe of Hot Electron and Hole Transfer from Colloidal CsPbBr3 Perovskite Nanocrystals

Sohini Sarkar, Vikash Kumar Ravi, Sneha Banerjee, Gurivi Reddy Yettapu, Ganesh B Markad, Angshuman Nag, and Pankaj Mandal

http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.7b02003?mi=aayia761&af=R&AllField=nano&target=default&targetTab=std

Colloidal all inorganic CsPbX3 (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 (THz) spectroscopy (TRTS) we have measured the kinetics of photogenerated electron and hole transfer processes in CsPbBr3 NCs in presence of benzoquinone (BQ) and phenothiazine (PTZ) molecules as electron and hole acceptors, respectively. Efficient hot electron/hole transfer with a sub-300 fs timescale 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 timescales of 20-50 ps for electrons and 137-166 ps for holes. This work suggests that suitable interfaces of CsPbX3 NCs with electron and hole transport layers would harvest hot carriers, increasing the photovoltaic and photocatalytic efficiencies.