Understanding Differences in the Crystallization Kinetics between One-Step Slot-Die Coating and Spin Coating of MAPbI3 Using Multimodal In Situ Optical Spectroscopy

Konstantin Schötz,Albert J.J.M Breemen,Gerwin H Gelinck,Eva M Herzig,Harrie Gorter,Fabian Panzer,Arjan Langen,Yulia Galagan,Ilker Dogan,Christopher Greve

doi:10.29363/nanoge.nfm.2021.187

Konstantin Schötz, Albert J.J.M Breemen + Show 8 more

Open Access

https://doi.org/10.29363/nanoge.nfm.2021.187

Copy DOI

Abstract

To develop a detailed understanding about halide perovskite processing from solution, the crystallization processes are investigated during spin coating and slot-die coating of MAPbI3 at different evaporation rates by simultaneous in situ photoluminescence, light scattering, and absorption measurements. Based on the time evolution of the optical parameters it is found that for both processing methods initially solvent-complex-structures form, followed by perovskite crystallization. The latter proceeds in two stages for spin coating, while for slot-die coating only one perovskite crystallization phase occurs. For both processing methods, it is found that with increasing evaporation rates, the crystallization kinetics of the solvent-complex structure and the perovskite crystallization remain constant on a relative time scale, whereas the duration of the second perovskite crystallization in spin coating increases. This second perovskite crystallization appears restricted due to differences in solvent-complex phase morphologies from which the perovskite forms. The work emphasizes the importance of the exact precursor state properties on the perovskite formation. It further demonstrates that detailed analyses of multimodal optical in situ spectroscopy allows gaining a fundamental understanding of the crystallization processes that take place during solution processing of halide perovskites, independent from the specific processing method.

Highlights

Since the first reports on metal halide perovskites applied as absorber material in perovskite solar cells (PSCs), the efficiency of the latter has increased rapidly and is at 25.5%.[1,2,3,4] most highly efficient PSCs are processed on millimeter lab-scale dimensions using spin coating.[5,6,7,8,9,10,11] To process perovskite layers from solution on a larger scale, methods such as slot-die coating are relevant
It further demonstrates that detailed analyses of multimodal optical in situ spectroscopy allows gaining a fundamental understanding of the crystallization processes that take place during solution processing of halide perovskites, independent from the specific processing method
We investigated in detail the crystallization processes taking place during the one-step solution processing of MAPbI3 via spin and slot-die coating using multimodal optical in situ spectroscopy

Summary

Introduction

Since the first reports on metal halide perovskites applied as absorber material in perovskite solar cells (PSCs), the efficiency of the latter has increased rapidly and is at 25.5%.[1,2,3,4] most highly efficient PSCs are processed on millimeter lab-scale dimensions using spin coating.[5,6,7,8,9,10,11] To process perovskite layers from solution on a larger scale, methods such as slot-die coating are relevant. With slot-die coating, efficiencies of larger-scale PSCs are typically lower than their spin-coated counterparts.[6,7,11] The main reason for this processingdependent efficiency gap is seen in differences in the final layer properties that follow from the high complexity of the perovskite film evolution.[8,11,12]. Numerous works investigated the perovskite formation process using in situ characterization methods.[6,13,14,15,16,17,18] Besides scattering techniques,[19,20,21,22,23,24] optical spectroscopy,[25,26,27,28] with, e.g., absorption

Results

Discussion

Conclusion