Giant electric field dependent hole mobility of CsPbBr3 nanocrystals films

Abstract

Colloidal CsPbBr3 nanocrystals are emerging as solution-processed semiconductors to fabricate advanced optoelectronic devices. Carrier mobility of nanocrystals films plays a crucial role in determining the performance of these devices. In this work, we measured the hole- and electron- only devices based on CsPbBr3 nanocrystals with different size. The zero field hole and electron mobility of CsPbBr3 nanocrystals films show size dependence. The zero field hole mobility increase from 0.39 × 10-9 to 2.62 × 10-9 cm2 V-1 s-1 and the zero field electron mobility increase from 0.54 × 10-8 to 4.36 × 10-8 cm2 V-1 s-1 with their average diameter increasing from 9 nm to 26 nm. With the electric field increasing from 0 to 50 MV/m, the hole mobility of CsPbBr3 nanocrystals films increase by 2-3 orders of magnitude. The electric field dependent coefficient (α), that describes the electric field dependence of hole mobility, decreases from 6.5×10-4 to 5.0×10-4 with their size increasing. In addition, we also determined the carrier mobility of CsPbBr3 nanocrystals with different ligands. By combining the calculation of charging energy, Monte Carlo simulations and Wentzel-Kramers-Brillouin approximation, we also theoretically illustrate the influence of size, ligand and electric field on the hole mobility of CsPbBr3 nanocrystals. The insights into the hole mobility of CsPbBr3 nanocrystals provides great chance to design new generation nanocrystals based devices.