Performance of different anti-reflection coating and TCO layers for kesterite based thin film photovoltaic devices using Essential Macleod simulation program

Optical losses at the front stack interface of thin film photovoltaic (PV) devices is responsible for ~4% loss of light reaching the active layer. The primary aim of this simulation studies is to obtain the least possible reflectance at the front surface of kesterite CZTS and CZTSe based thin film devices, considering its effects with and without the antireflection coatings. Essential Macleod simulation software was employed to theoretically refine the optical thicknesses of Zinc oxide (ZnO) window layers and different transparent conductive oxide (TCO) layers like aluminium doped ZnO (ZnO:Al) and Indium doped Tin oxide (ITO). The Minimum reflectance values within a wide wavelength range from 300 to 800 nm were recorded. Moreover, to obtain complete transmittance from UV to visible region, low refractive index materials such as MgF2, Al2O3 and CeF3 were taken as different antireflective layers (ARC) and their corresponding reflectance and transmittance were simulated. The optical thicknesses of ZnO with different TCO and ARC layers were optimised to achieve a low reflectance of less than 5% for the better performance of the thin film devices. Based on the best possible optimisation, Al2O3 antireflection layer with ZnO:Al (transparent conductive layer) and ZnO (window layer) exhibited a reflectance of less than 1% within the mid-wavelength range from 500 to 800 nm with the optimised thicknesses suitable for thin film devices.