The solar cell characterised in this work follows the device architecture FTO/ZnMgO/Te/Se/MoO x /Au, fabricated using physical vapour deposition techniques. Details of the fabrication process are provided in Ref. 18. Suns-V oc measurements of the photovoltaic device were performed using the accessory stage of a WCT-120 from Sinton Instruments. This setup features an illumination sensor calibrated for intensities ranging from 0.006 to 6 suns, and the temperature of the sample chuck controlled at 25 C.