Analytical modeling and performance enhancement of Cu(In,Ga)Se₂ chalcopyrite solar cells through nanostructure integration

CuGaSe₂ (CGSe), CuInSe₂ (CISe), and Cu (In,Ga)Se₂ (CIGSe) are highly attractive chalcopyrite materials due to their exceptional optoelectronic properties, which make them a suitable candidate for solar cells application. However, highest power conversion efficiency (PCE) reported for these photo absorber materials is close to 20%, which is far below the theoretical limit. It is possible to approach the theoretical limit by incorporating nanostructures into the cell, which initiates the sub-bandgap (E_g) absorption by forming an intermediate band (IB). In this study, CISe nanostructures are incorporated within the CGSe host material to form a CGSe/CISe quantum wells (QWs). This method utilizes the host semiconductor's wider E_g to maintain the open-circuit voltage (V_oc) values that are comparable to those reported for CGSe solar cells. The study examines the effects of QWs thickness, QWs number, and Ga/(Ga+In) compositional ratio on the characteristics of solar cells. Results indicate that incorporating 50 QWs with thicknesses ranging from 20 to 150 nm and Ga/(Ga+In) compositional ratios of about 0.2 and 0.8, respectively, can enhance PCE, further highlighting the importance and positivity of nanostructures. In addition, improvements in short-circuit current density, V_oc, and overall PCE are also observed than the optimized device without nanostructures. The study proposes a promising approach to improve the photo absorption, carrier separation and thereby over all solar cell performance based on Chalcopyrite heterostructure QWs.