Development of CdTe thin film solar cells using a hybrid wet chemical hydrothermal and doctor blade technique

Cost-effective and scalable solution-based methods have been used to fabricate CdS/CdTe solar cells. CdTe layers were obtained via a doctor-blade method using the hydrothermally synthesized CdTe powder. The CdS layers were grown on fluorine-doped tin oxide-coated glass-substrates using chemical bath deposition. The Cd concentration was changed systematically to control the composition, which enabled the examination of the impact of non-stoichiometric Te excess defects on the CdTe layers. The effect of sintering temperature was investigated by examining various properties. The sintering temperature can lead to improved crystallinity, grain size, and compactness of CdTe films. Current density-voltage, external quantum efficiency (EQE), and capacitance-voltage measurements were conducted to characterize the CdTe solar cells. Optimizing the CdTe stoichiometry can enhance the EQE and power conversion efficiency (PCE). We report a PCE of 2.91% and a peak EQE of nearly 60% for stoichiometric CdTe samples. Capacitance-voltage measurements showed a higher carrier concentration and flatband potential in stoichiometric samples.