Characterization of 2D-PEA2SnI4 perovskite thin films grown by sequential physical vapor deposition

Abstract

2D-PEA 2 SnI 4 perovskite thin films were prepared by sequential physical vapor deposition (SPVD) technique. The effect of low substrate deposition temperature, annealing time, and PEAI thickness on structural, optical, and morphological properties of 2D-PEA 2 SnI 4 thin films was investigated. The results show that early-stage crystallization of SnI 2 films before subsequent evaporation of PEAI hinders the efficient interdiffusion of the perovskite precursors. Films deposited at low substrate temperature (∼18 °C) exhibited ∼300 % carrier lifetime improvement from 0.14 to 0.56 ns, suggesting a reduction of defect density and suppression of nonradiative recombination. FE-SEM micrographs revealed uniformly deposited films with densely packed grain size ranging from 92.50 to 453.1 nm and minimum pinholes. AFM results showed that surface roughness decreased from 138.2 to 50.99 nm as annealing time increased from 0 to 60 min. Similarly, surface roughness increased from 18.02 to 50.99 nm as PEAI thickness increased from 40 to 500 nm. XRD results revealed an improvement in crystallinity and average crystallite size as annealing time and PEAI thickness increased. This work suggests a way of improving the reaction between 2D-Sn-based perovskite precursors using the SPVD technique by controlling the substrate temperature and highlighting the role of substrate deposition temperature, film thickness, and annealing time towards crystallization of the perovskite. • Synthesis of 2D-PEA 2 SnI 4 perovskite by SPVD was demonstrated. • Low substrate temperature ensured that growth rate does not surpass nucleation rate. • Annealing greatly improved the optical, morphological and structural properties of 2D films.