Defect density optimization is an optimization technique to increase cell performance. There is a direct effect of defect density on device output parameters. The recombination rate is increased with the increment of defect density, which reduces the carrier lifetime and diffusion length of the carrier. Hence, efficiency is also deduced. In this section, both cells are simulated with a defect density of 1.00×10 10 (1/cm 3 ) to 1.00×10 18 (1/cm 3 ).