Silicon heterojunction solar cells (IMAGE) University of Utah Caption A cartoon schematic of a silicon heterojunction solar cell and it's photo-generated charges. The numbers correspond to three of the major electrical noise signals identified by the researchers in the study. These noise signals occur when 1) electrons and 3) holes pass through the layers and 2) when charges are trapped at the boundary between the silicon and the transparent ITO layer at the front of the device. Credit Kevin Davenport Usage Restrictions Non-commercial with attribution. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.