Light soaking of silicon heterojunction solar cells by applying high-intensity line-shaped laser scans

Intensive light soaking (LS) is an effective post-treatment to boost the efficiency of hydrogenated amorphous Si (a-Si:H)/crystalline Si (c-Si) heterojunction solar cells. To date, devices have been annealed and illuminated with an intensity of up to 100 suns. Here, the potential of using an ultra-high-density light source equivalent to >10,000 suns is investigated by a scanning continuous-line-shaped infrared laser. It is clarified that the LS effect involves a reordering of H in the a-Si:H layers, which serves as the critical time-limiting process, triggered by carrier injection in c-Si and the associated induced heating. As a result, the local LS treatment increases carrier lifetime and efficiency by up to 400% and 1.3 %abs, respectively. While a laboratory-scale laser was used here, LS treatment via laser (scanning) offers substantial potential for scalability by employing an industrial laser with a larger irradiation area and higher power.