Optical design and analysis of textured a-Si solar cells

The effect of texture on enhancement and losses in photocurrent in a-Si solar cells is explored using PVOPTICS software and measurements on a-Si device structures. The texture angle has a major impact on light trapping and internal reflection. Increasing the angle causes better internal trapping in the i-layer, but also higher SnO₂/a-Si reflection losses, as well as SnO₂ and metal absorption losses. Parasitic absorption in the textured SnO₂ due to back reflected light is 1-2 mA/cm² for typical designs. N-i-p cells have a fundamental advantage over p-i-n cells since the textured TCO is at the rear of the device leading to lower losses.