# Optical Properties and Growth of the (100) Crystal-Faced MAPbBr3 Film on TiN-Buffered MgO Substrate

## TL;DR

This paper describes a new method to grow high-quality MAPbBr3 films on a TiN-buffered MgO substrate, improving their optical performance for optoelectronic devices.

## Contribution

A scalable fabrication method for (100)-oriented MAPbBr3 films using a TiN buffer layer is introduced, enhancing optical properties through reduced strain.

## Key findings

- Post-annealing improved crystal orientation with a 19-fold increase in the (100) to (110) peak intensity ratio.
- Annealed films showed a 1.8-fold increase in photoluminescence intensity and a 20.8% narrower PL FWHM.
- The TiN buffer reduced lattice mismatch to 0.66%, resulting in suppressed non-radiative recombination and better optical homogeneity.

## Abstract

The growth of MAPbBr3 crystal-faced films is a critical challenge for advancing optoelectronic devices. This study presents a methodology for fabricating a (100) crystal-faced MAPbBr3 film on a lattice-matched MgO/TiN composite substrate using a localized thermally driven inverse temperature crystallization technique. The metallic TiN buffer layer offers a 0.66% lattice mismatch to MAPbBr3, minimizing interfacial strain. Furthermore, the orientation enhancement of the film induced by post-annealing was confirmed by X-ray diffraction, with the (200) peak FWHM decreasing from 0.042° to 0.028° and the intensity ratio of the (100) to (110) peaks increasing from 6.89 to 19.00. These structural improvements directly translate into enhanced optical performance. The annealed sample exhibited sharper Raman phonon modes at 49 cm−1 and 151 cm−1, a 1.8-fold photoluminescence intensity enhancement, and a 20.8% narrowing of the PL FWHM at 536 nm. Additionally, UV-Vis spectroscopy confirms the bandgap of MAPbBr3, displaying a steeper absorption edge with a bandgap of 2.30 eV. These metrics provide compelling evidence of suppressed non-radiative recombination and improved optical homogeneity after annealing. By integrating TiN as an electron-transport and buffer layer to reduce strain and lattice mismatch, the MgO/TiN/MAPbBr3 architecture offers a scalable, scientifically grounded pathway to improve MAPbBr3’s optical performance.