A Symphony of Layers: Optimizing Architecture for High-Efficiency Sb2Se3 Devices

Antimony selenide, Sb2Se3, has emerged as a promising material for p-type absorbers in thin-film photovoltaics, boasting an optimal band-gap (~1.2 eV) and a high absorption coefficient (>105 cm-1), which contribute to record cell efficiencies exceeding 10%. The photovoltaic parameters are significantly influenced by its highly anisotropic crystal structure and the absorber's very low free carrier density. This study explores various strategies to enhance the photovoltaic properties of Sb2Se3-based solar cells. Two distinct growth techniques, Radio Frequency Magnetron Sputtering (MS) and Pulsed Electron Deposition (PED), were employed to deposit Sb2Se3. The dominant crystallographic orientations were analyzed in relation to the growth techniques, deposition parameters, and different substrates used. Solar cells incorporating these absorber layers demonstrated a strong dependence of short circuit current density on the (Sb4Se6)n ribbon orientation. Additionally, Cu was evaluated as a p-type dopant for Sb2Se3 thin-films, resulting in an improvement by approximately two orders of magnitude in Cu-doped Sb2Se3 films. Corresponding solar cells showed conversion efficiency exceeding 5% and open circuit voltage > 510 mV. Furthermore, several cell architectures featuring different electron transport layers (CdS, TiO2, ZTO) and hole transport layers (Mo, FTO, MoO3, WO3) were modelled, underscoring the importance of band alignment in enhancing the Fill Factor and overall solar cell efficiency.