# Single-crystalline MAPbCl3 thin-films for photo- and X-ray voltaics

## TL;DR

Single-crystalline MAPbCl3 thin films are fabricated for transparent solar cells and X-ray voltaics, achieving high voltages and power conversion.

## Contribution

A method to grow single-crystalline MAPbCl3 thin films via space-confined inverse temperature crystallization is demonstrated.

## Key findings

- Single-crystalline MAPbCl3 solar cells achieved a VOC of 1.64 V and 1.1% PCE.
- MAPbCl3 films demonstrated X-ray voltaic performance with a VOC of 0.89 V and 3.57 μW cm−2 output power.

## Abstract

3 eV wide bandgap methylammonium lead trichloride (MAPbCl3) perovskites are promising for transparent solar cells, smart windows, and the internet of things (IoTs). However, it is challenging to crystallize uniform polycrystalline MAPbCl3 thin films from solution. On the other hand, single-crystalline MAPbCl3 can be grown as relatively uniform thin films. In this work, we demonstrate the fabrication of single-crystalline MAPbCl3 thin films on conductive glass substrates via a space-confined inverse temperature crystallization (ITC). The perovskite films exhibit no emission peaks from states located deep within the bandgap, confirming a less defective perovskite bulk than its polycrystalline counterpart. The resulting perovskite solar cells (PSCs) yield an open-circuit voltage (VOC) of up to 1.64 V and a high power conversion efficiency (PCE) of 1.1% under one sun irradiation. Additionally, the MAPbCl3 is studied for its conversion of X-rays into electrical energy, i.e., “X-ray-voltaics”, demonstrating a VOC of 0.89 V together with an output power of 3.57 μW cm−2 at an X-ray tube voltage of 60 kV (4900 μW cm−2).

Single-crystalline MAPbCl3 thin films grown via space-confined ITC enable transparent solar cells with a VOC of 1.64 V and 1.1% PCE. They also advance X-ray voltaics, showing 0.89 V VOC and 3.57 μW cm−2 output power under X-ray irradiation.