Enhanced amorphous-silicon solar cell efficiency through a wet etched aluminum-doped ZnO pattern replication using direct printing lithography

To generate a high degree of scattering at the front transparent conductive oxide of amorphous silicon thin film solar cells, aluminum-doped zinc oxide films wer etched using an acidic solution. Unfortunately, the sharp protrusions and deep valleys on these textured surfaces can cause defects. Therefore, a random nano-micro pattern was first formed on a glass substrate using a nanoimprint lithography technique; then a thick aluminum-doped zinc oxide layer was deposited atop this, covering the rough surface such that its surface is smoother than that of the patterned glass substrate, allowing for the growth of good quality thin film solar cells. The random nano-micro pattern on the glass substrate scatters the incident light, increasing its path length and probability of light absorption, enhancing the short circuit current density and power conversion efficiency. The solar cells deposited on the aluminum-doped zinc oxide/nano-micro patterns demonstrated an increased short circuit current without any reduction in either the open circuit voltage or fill factor. Relative to an aluminum-doped zinc oxide/flat glass substrate, the short circuit current and power conversion efficiency enhancement of a solar cell on an aluminum-doped zinc oxide/nano-micro patterned glass substrate increased by 8.2% and 12.7%, respectively.