Zn₃P₂ and Cu₂O Substrates for Solar Energy Conversion

Citation

Kimball, Gregory Michael (2012) Zn₃P₂ and Cu₂O Substrates for Solar Energy Conversion. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Q4F1-H538. https://resolver.caltech.edu/CaltechTHESIS:10302011-182613259

Abstract

Zinc phosphide (Zn₃P₂) and cuprous oxide (Cu₂O) are promising and earth-abundant alternatives to traditional thin film photovoltaics materials such as CIGS, CdTe, and a-Si. We have prepared high purity substrates of Zn₃P₂ from elemental zinc and phosphorus, and Cu₂O by the thermal oxidation of copper foils, to investigate their fundamental material properties and potential for solar energy conversion. Photoluminescence-based measurements of Zn₃P₂ substrates have revealed a fundamental indirect band gap at 1.38 eV and a direct band gap at 1.50 eV, with time-resolved data indicating minority carrier diusion lengths of ≥7 μm. Solar cells based on Mg/Zn₃P₂ junctions with solar energy conversion efficiency reaching 4.5% were examined by composition profiling to elucidate the passivation reaction between Mg metal and Zn₃P₂ surfaces. Semiconductor/liquid junctions incorporating Cu₂O substrates exhibited open-circuit voltage, V_oc, values in excess of 800 mV and internal quantum yields approaching 100% in the 400–500 nm spectral range.

Thesis Files