# Color-Tunable and Efficient CsPbBr3 Photovoltaics Enabled by a Triple-Functional P3HT Modification

## TL;DR

Scientists improved the performance of CsPbBr3 solar cells by using a special polymer that enhances light absorption, improves energy transfer, and stabilizes the material.

## Contribution

A triple-functional P3HT modifier was introduced to enhance CsPbBr3 solar cells with tunable color and improved efficiency.

## Key findings

- P3HT acted as an assistant photoactive layer, enhancing light absorption and broadening the spectrum response.
- P3HT improved hole transport and formed stable Pb-S bonds, acting as a defect passivator.
- Optimal P3HT concentration increased power conversion efficiency from 6.86% to 8.71% with better stability.

## Abstract

All inorganic CsPbBr3 possesses ideal stability in halide perovskites, but its wide bandgap and relatively poor film quality seriously limit the performance enhancement and possible applications of perovskite solar cells (PSCs). In this work, a triple-functional poly(3-Hexylthiophene) (P3HT) modifier was introduced to realize color-tunable semi-transparent CsPbBr3 PSCs. From the optical perspective, the P3HT acted as the assistant photoactive layer, enhanced the light absorption capacity of the CsPbBr3 film, and broadened the spectrum response range of devices. In view of the hole transport layer, P3HT modified the energy level matching between the CsPbBr3/anode interface and facilitated the hole transport. Simultaneously, the S− in P3HT formed a more stable Pb-S bond with the uncoordinated Pb2+ on the surface of CsPbBr3 and played the role of a defect passivator. As the P3HT concentration increased from 0 to 15 mg/mL, the color of CsPbBr3 devices gradually changed from light yellow to reddish brown. The PSC treated by an optimal P3HT concentration of 10 mg/mL achieved a champion power conversion efficiency (PCE) of 8.71%, with a VOC of 1.30 V and a JSC of 8.54 mA/cm2, which are remarkably higher than those of control devices (6.86%, 1.22 V, and 8.21 mA/cm2), as well its non-degrading stability and repeatability. Here, the constructed CsPbBr3/P3HT heterostructure revealed effective paths for enhancing the photovoltaic performance of CsPbBr3 PSCs and boosted their semi-transparent applications in building integrated photovoltaics (BIPVs).