# Thermally Fine-Tuned NiOx–MAPbI3 Interfaces Enabled by a Polymeric Surface Additive for High-Sensitivity Self-Powered Photodetectors

## TL;DR

A new method using a polymer additive improves the performance of self-powered photodetectors made with perovskite and nickel oxide layers.

## Contribution

A polymeric surfactant enables thermal fine-tuning of NiOx–MAPbI3 interfaces without forming an interlayer, enhancing photodetector performance.

## Key findings

- PTE incorporation increases external quantum efficiency at 640 nm from 78.7% to 84.6%.
- Noise-equivalent power decreases and detectivity increases under zero-bias operation.
- Devices retain fast temporal responses and kilohertz-level bandwidths without performance loss.

## Abstract

Self-powered perovskite photodiodes provide an attractive platform for low-power and high-sensitivity photodetection; however, their performance capabilities are often constrained by inefficient interfacial charge extraction and noise suppression. Here, we report a polymer-mediated interfacial engineering strategy for methylammonium lead iodide (MAPbI3) photodiodes by integrating thermally optimized nickel oxide (NiOx) hole-transport layers (HTLs) with a nonionic polymeric surfactant, poly(oxyethylene)(10) tridecyl ether (PTE). NiOx films annealed at 300 °C establish a favorable energetic baseline for hole extraction, while the ppm-level incorporation of PTE into the MAPbI3 precursor enables the molecular-scale modulation of the NiOx/MAPbI3 interface without forming an additional interlayer. The external quantum efficiency at 640 nm increases from 78.7% for pristine MAPbI3 to 84.1% and 84.6% for devices incorporating 30 and 60 ppm PTE, corresponding to enhanced responsivities of 406, 434, and 437 mA/W. These improvements translate into reduced noise-equivalent power and an increase in the noise-limited detectivity from 2.50 × 1012 to 2.76 × 1012 Jones under zero-bias operation. Importantly, enhanced sensitivity is achieved without compromising the dynamic performance, as all devices retain fast temporal responses and kilohertz-level bandwidths. These results establish polymeric-surfactant-assisted interfacial engineering as a scalable and effective platform for low-noise, high-sensitivity self-powered perovskite photodiodes for renewable-energy-integrated systems.