Exploring the Role of Temperature and Hole Transport Layer on the Ribbon Orientation and Efficiency of Sb2Se3 cells Deposited via Thermal Evaporation

Antimony selenide (Sb2Se3) has emerged as a promising candidate for next generation solar cell devices due to its non-toxicity, low cost, and earth abundance. Coupling these factors with its promising optoelectrical properties of its high absorption coefficient and almost ideal band gap for single-junction cells yields an incredibly attractive absorber material. Issues in the material come from poor carrier management, particularly in the mobility of photogenerated carriers within the absorber layer and through the immediate interfaces. The orientation of the (Sb4Se6)n ribbons grown via thermal evaporation was investigated by varying the deposition temperature and the post-annealing treatment. 300 °C as the deposition temperature was most conducive to promoting ribbon orientations which were perpendicular to the substrate. Annealing effects were shown to be able to induce crystallinity in films at a lower temperature than the deposition temperature as well as being able to influence orientation away from (hk0) orientations. Using these parameters, the effect of 15 nm thick NiOX and MoOX as Hole Transport Layer (HTL) materials deposited via electron-beam evaporation in antimony selenide solar cells is investigated in superstrate and substrate configurations. Notable improvements were found to the efficiency of the devices when NiOX was considered as the HTL, but a degradation occurred when fabricated with MoOX in superstrate configuration; substrate configuration was only viable with a NiOX HTL.