Insights on the Thermal Stability of the Sb₂Se₃ Quasi‐1D Photovoltaic Technology

This work explores the thermal stability of antimony‐based photovoltaic (PV) technologies investigating the effect of low‐temperature (50—350 °C) postdeposition annealings (PDAs) on bare Sb 2 Se 3 absorbers and complete SLG/Mo/Sb 2 Se 3 /CdS/i‐ZnO/ITO devices (5.7% power conversion efficiency with no anti‐reflecting coating or metallic grid). A comprehensive structural analysis by means of X‐ray diffraction and Raman spectroscopy, coupled with optoelectronic characterization, reveals clear evidences of a degradation process dominated by selenium diffusion. The degradation process is observed to start at low PDA temperatures as a shrinkage of the Sb 2 Se 3 unit cell. Further increasing the PDA temperature above 200 °C leads to the formation of Sb oxides and Se secondary phases in bare absorbers, and of CdS 1— x Se x in complete devices at the Sb 2 Se 3 front interface which completely degrade the heterojunction and kill device performance. Furthermore, a clear correlation is found between PV performance decrease and Sb 2 Se 3 layer lattice shrinkage with the increasing PDA temperature ( T > 50 °C). This is the first time that thermal instability is reported for the Sb 2 Se 3 compound at temperatures commonly used during PV module fabrication processes such as emitter/transparent conducting oxide deposition or encapsulation.