Abstract
The invention provides a solar cell whose substrate has multiple deeply etched holes. The substrate is made of a semiconductor with single-crystalline, polycrystalline, or amorphous structure, and has a plurality of deep holes formed by etching or other types of processing. The depth of each hole is at least one fourth of the substrate's thickness, or the distance from the bottom of each hole to the other side of the substrate is no more than 50 mm. The solar cell as such has a low probability of carrier recombination and high photovoltaic conversion efficiency.