Heteroepitaxial Cu₂O thin film solar cell on metallic substrates

Heteroepitaxial, single-crystal-like Cu₂O films on inexpensive, flexible, metallic substrates can potentially be used as absorber layers for fabrication of low-cost, high-performance, non-toxic, earth-abundant solar cells. Here, we report epitaxial growth of Cu₂O films on low cost, flexible, textured metallic substrates. Cu₂O films were deposited on the metallic templates via pulsed laser deposition under various processing conditions to study the influence of processing parameters on the structural and electronic properties of the films. It is found that pure, epitaxial Cu₂O phase without any trace of CuO phase is only formed in a limited deposition window of P(O₂)-temperature. The (00l) single-oriented, highly textured, Cu₂O films deposited under optimum P(O₂)-temperature conditions exhibit excellent electronic properties with carrier mobility in the range of 40-60 cm² V^-1 s^-1 and carrier concentration over 10¹⁶ cm^-3. The power conversion efficiency of 1.65% is demonstrated from a proof-of-concept Cu₂O solar cell based on epitaxial Cu₂O film prepared on the textured metal substrate.