Characterisation of Next-Generation Solar Cell Materials and Devices

Abstract

This work consists of characterisation of different electrodeposited semiconductor layers to be used in developing CdTe-based thin-film solar cells with a novel structure having p-type window. Comprehensive details of the electrical, structural, and morphological techniques that have been used to learn how to optimize, characterise, and fabricate the semiconductor materials Cadmium telluride (CdTe) based solar cells. These techniques have been applied on Cadmium sulphide (CdS) as-deposited (AD) and heat treated (HT) samples, and Cadmium manganese telluride (CdMnTe) as-deposited (AD) and Cadmium chloride treated (CCT) samples. The observation of the CdS layers shows n-type conductivity for all the layers in different growth voltage, where the heat treated samples seems more consistent in terms of Photoelectrochemical (PEC) cell signals than the as-deposited. The best bandgap for the CdS that has been observed is around 2.4 eV and 2.38 eV at the growth voltage 1450 mV for the AD and HT respectively. The X-ray diffraction (XRD) study shows a cubic/hexagonal shape structure for the AD-CdS, while the HT transferred more towards the hexagonal phase. The CdMnTe as-deposited layers shows p-type, n-type, and ptype conductivity type at different growth voltage respectively. Whereas the CCT layers shows ptype conductivity. The CdMnTe layers show two bandgaps during the observation, the first one is observed around 1.45 eV and the second one is observed between 1.8-1.9 eV for both the CdMnTe samples. The XRD analysis shows a cubic structure for both samples. Scanning electron microscopy (SEM) study, and Energy dispersive X-ray (EDX) has been applied to investigate the morphological and compositional characterisation of the both materials respectively. The device characterisation has been practised by using CdTe based solar cells device previously prepared based on n-window.