Optical Dispersion Data Analysis of Single‐Crystal CH3NH3PbBr3 for Optimized Perovskite Solar Cell Active Layer Absorptance

• Published in: Advanced photonics research Vol. 5; no. 10
• Main Authors: McCleese, Christopher L., Brennan, Michael C., Episcopo, Nathan, Sun, Lirong, Hong, Nina, Ramana, Chintalapalle V., Grusenmeyer, Tod A., Stevenson, Peter R.
• Format: Journal Article
• Language: English
• Published: Wiley-VCH 01-10-2024
• Subjects: absorption coefficients; extinction coefficientsoptical properties; perovskite solar cells; refractive indices
• ISSN: 2699-9293; 2699-9293
• DOI: 10.1002/adpr.202400019

Proper derivation of CH3NH3PbX3 (MAPbX3; where X = Cl−, Br−, I−) optical constants is a critical step toward the development of high‐performance perovskite devices. To date, the optical dispersions at all wavelengths have been inconsistently characterized by under‐approximating or omitting anomalous spectral features. Herein, a rigorous optical dispersion data analysis of single‐crystal MAPbBr3 involving variable‐angle spectroscopic ellipsometry data appended with transmission intensity data is presented. This approach yields a more robust derivation of the refractive index and extinction coefficient for both anomalous (absorptance) and normal (no absorptance) optical dispersion regimes. Using the derived optical constants, illustrative modeled perovskite solar cell device designs are presented in relation to nonrealistic designs prepared using representative optical constants reported in the literature. In comparison, the derived optical constants enables the modeling of layer thicknesses to maximize absorption by the active layer (MAPbBr3) and minimize parasitic optical absorptance by the nonactive layers at broad angles of incidence (≈0°–70°). This robust derivation of MAPbBr3 optical constants is expected to impact the optical dispersion data analysis of all perovskite analogs and expedite targeted development of, for example, solar cell, light‐emitting diode, photo‐ and X‐ray/γ‐ray detector, and laser system technologies.
This article presents rigorous optical dispersion analyses from the ultraviolet to the shortwave infrared of large‐area CH3NH3PbBr3 single crystals with high‐quality surface finishes. The analyses yield robust optical constants for all wavelength regimes by appending variable‐angle spectroscopic ellipsometry with corresponding transmission measurements. Derived optical constants permit modeling of perovskite solar cells with optimized solar radiation absorption.