# Scalable Phosphorus Doping of p‑Type FeS2 Microcrystals for Photovoltaic Applications

## TL;DR

This paper introduces a scalable method to create p-type FeS2 microcrystals using phosphorus, which could lead to low-cost solar cells.

## Contribution

The first scalable method to achieve p-type conductivity in pyrite FeS2 using phosphorus via the liquid salt growth method.

## Key findings

- A FeS + P precursor containing FeP4 phase successfully induces p-type conductivity in FeS2 microcrystals.
- Elemental phosphorus is thermodynamically unsuitable for doping FeS2.
- Hot probe measurements confirm the p-type behavior of the doped microcrystals.

## Abstract

Pyrite FeS2 is an Earth-abundant semiconductor
with
the potential to deliver the lowest-cost photovoltaic solutions available
today. However, progress has been limited by poor control over doping
and surface defect chemistry, leading to consistently low device efficiencies.
In this work, we demonstrate for the first time a truly scalable approach
to achieve p-type conductivity of pyrite microcrystals
using phosphorus via the liquid salt growth method. We systematically
explore three established doping strategies for semiconductors and
identify the successful route involving the use of a FeS + P precursor
containing the FeP4 phase. Hot probe measurements confirm p-type conductivity. Neutral sources such as elemental phosphorus
are shown to be thermodynamically unsuitable and fail to induce p-type behavior. This study also identifies a phosphorus
compound suitable for producing p-type FeS2 microcrystals, offering a new foundation for the development of
pyrite photovoltaic devices.