Chemical Vapor Deposited Mixed Metal Halide Perovskite Thin Films.

Siphesihle Siphamandla Magubane,Siphelo Ngqoloda,Franscious Cummings,Christopher Mtshali,Amogelang Sylvester Bolokang,Christopher Joseph Arendse

doi:10.3390/ma14133526

Siphesihle Siphamandla Magubane, Siphelo Ngqoloda + Show 4 more

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https://doi.org/10.3390/ma14133526

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Abstract

In this article, we used a two-step chemical vapor deposition (CVD) method to synthesize methylammonium lead-tin triiodide perovskite films, MAPb1−xSnxI3, with x varying from 0 to 1. We successfully controlled the concentration of Sn in the perovskite films and used Rutherford backscattering spectroscopy (RBS) to quantify the composition of the precursor films for conversion into perovskite films. According to the RBS results, increasing the SnCl2 source amount in the reaction chamber translate into an increase in Sn concentration in the films. The crystal structure and the optical properties of perovskite films were examined by X-ray diffraction (XRD) and UV-Vis spectrometry. All the perovskite films depicted similar XRD patterns corresponding to a tetragonal structure with I4cm space group despite the precursor films having different crystal structures. The increasing concentration of Sn in the perovskite films linearly decreased the unit volume from about 988.4 Å3 for MAPbI3 to about 983.3 Å3 for MAPb0.39Sn0.61I3, which consequently influenced the optical properties of the films manifested by the decrease in energy bandgap (Eg) and an increase in the disorder in the band gap. The SEM micrographs depicted improvements in the grain size (0.3–1 µm) and surface coverage of the perovskite films compared with the precursor films.

Highlights

Three-dimensional (3-D) organo-lead halide perovskites, which form a perovskite structure of ABX3, have received tremendous research interest over the past decade [1]
There is an ongoing d4e.bCaotenaclbuosuitotnhse origin and magnitude of the bandgap bowing in mixed metal perovskites; whethWereitsiysndthuestiozethdemchixemedicmaleetfafel chtsa,lisdtreucpteurroavl sekffietectst,hoinr aficlmomsbbinyatwiono osftebpo-tsheq[8u1e–n8t3ia].l chemical vapor deposition (CVD), which included the deposition of mixed SnCl2-PbI2 compound as the precursor films and subsequently exposing them to methylammonium iodide (MAI) for conversion into perovskites
A controlled the concentration of Sn in the perovskite films was demonstrated, as quantified by Rutherford backscattering spectroscopy (RBS)

Summary

Introduction

Three-dimensional (3-D) organo-lead halide perovskites, which form a perovskite structure of ABX3, have received tremendous research interest over the past decade [1]. We have seen tremendous progress in the solar cell (SC) performance from 3.8% to 25.5% power conversion efficiency (PCE) of these lead-based perovskite SCs. As a result, we have seen tremendous progress in the solar cell (SC) performance from 3.8% to 25.5% power conversion efficiency (PCE) of these lead-based perovskite SCs This is due to their high optical absorption coefficients, high charge carrier mobilities, long charge carrier diffusion lengths, low exciton binding energy, bandgap tunability, and low-temperature solution processability [2,3,4,5,6,7,8,9,10]. The relatively wide Eg (1.5–2.2 eV) of organo-lead halide perovskite dramatically limits the sensitivity of the film in the IR region of the solar spectrum [13]. Another major drawback that is associated with lead-based perovskites is the toxicity of the lead (Pb) element and its compounds, which pose threats to the environment and human well-being, restricting the commercialization of Pb-based perovskite solar cells (PSCs) [7,14,15,16,17,18]

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