Enhancement of optical properties for all-inorganic perovskite composite by block copolymer nanopatterning

Abstract

All-inorganic perovskite has good thermal and chemical stability, easily tunable band gap by changing the elemental composition, high absorption coefficient, and cost-effectiveness. Owing to these advantages, it is widely accepted in next-generation optoelectronics. However, surface defects and non-uniform film morphology, which are formed while fabricating, induce non-radiative recombination and cause high leakage current, followed by lower device performance. Previously, numerous interfacial engineering studies using Lewis base were proceeded in order to passivate the defects or improve the morphology. Here, motivated from the previous research, block copolymer nanopatterning was applied as substrate layer for perovskite film to maximize the interfacial engineering effect. Among various block copolymers, polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) was adopted since it contains Lewis base oxygen group and increases the surface area via surface-reconstruction. PS-b-PMMA nanopatterning leads to defect passivation and uniform morphology by altering the interface of all-inorganic perovskite composite film. In short, the introduction of block copolymer nanopattern increased the photoluminescence (PL) and photoluminescence quantum yield (PLQY) by 13.9 %, 4.8 %, respectively, and the average carrier lifetime by 4.6 times compared to the existing perovskite film.