The optoelectronic properties of a selected group of Cu-III-VI2 chalcopyrites-based materials are deeply investigated by using the modified Becke-Johnson (mBJ) potential, combined with DFT + U approach. The obtained results are further used to calculate these materials’ theoretical efficiency limit for solar cell applications. The bandgap findings indicate a reliable ±0.2 eV agreement. After evaluating the electronic and optical properties, the spectroscopic limited maximum efficiency (SLME) model was used as a metric for the screening. Besides the bandgap value considered in the Shockley–Queisser model, the SLME requires that the absorption spectra, the radiative recombination losses, and the absorber layer thickness must be considered to adequately calculate the efficiency of considered cells. Our findings unveil that some candidates, such as CuInS2, where an SLME of 30.25% is achieved at a film width of 500 nm can be classified in the category of materials with higher power conversion efficiency.