Du, T; Richheimer, F; Frohna, K; Gasparini, N; Mohan, L; Min, G; Xu, W; Macdonald, T J; Yuan, H; Ratnasingham, S R; Haque, S; Castro, F A; Durrant, J R; Stranks, S D; Wood, S; McLachlan, M A; Brisco, J (2022) Overcoming Local Inhomogeneities in Thin-film Perovskites via Exceptional Post-Annealing Grain Growth for Enhanced Photodetection. Nano Letters, 22 (3). pp. 979-988.

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Abstract

Antisolvent-assisted spin coating has been widely used for fabricating metal halide perovskite films with smooth and compact morphology, suitable for thin-film optoelectronic devices. However, local inhomogeneities exist in these films owing to rapid perovskite crystallization, undermining their overall optoelectronic performance. Here we show that by relaxing the requirement for film smoothness and driving film morphology towards minimized surface energy, outstanding quality can be obtained in the polycrystalline films. The morphology transition driven by post-deposition crystal growth both reduces and reorganizes the grain boundaries (GB), eliminating local defective clusters and thus highly emissive GBs are observed. The obtained film shows homogeneous inter-grain and intra-grain photoconduction, where the GBs exhibit negligible heterogeneity compared to grain interiors. Overcoming these local performance-limiting inhomogeneities results in enhancement of photoresponse [mA cm-2 W-1] to low-light illuminations by up to 40 fold, yielding high-performance photodiodes with specific detectivity > 1013 Jones and superior low-light detection.

Item Type:	Article
Keywords:	Thin-film perovskites, nanoscale inhomogeneities, grain growth, photoresponse, photodetection
Subjects:	Electromagnetics > Electromagnetic Materials
Divisions:	Electromagnetic & Electrochemical Technologies
Identification number/DOI:	10.1021/acs.nanolett.1c03839
Last Modified:	09 Mar 2022 15:57
URI:	https://eprintspublications.npl.co.uk/id/eprint/9367