{'fraction_non_alphanumeric': 0.02765321375186846, 'fraction_numerical': 0.0, 'mean_word_length': 4.821739130434783, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Dependence of Open Circuit Voltage of Amorphous Silicon Solar Cells on Thickness and Doping Level of the p-Layer

We have focused on the thickness and the boron-doping concentration of the p-layer of amorphous silicon solar cells and systematically obtained data for open circuit voltage (Voc) and the built-in potential to reveal the mechanism causing a high Voc. A highly doped p-layer gives a higher built-in potential in the entire thickness range, but Voc is limited by the carrier recombination caused by the doping-induced defects. A low-doped p-layer causes a higher Voc in a sufficiently thick film because less carrier recombination occurs due to the lower density of the doping-induced defects. After light-soaking, significant Voc degradation occurs with the low-doped p-layer. The light-induced defects are not negligible compared with the initial defects in the low-doped p-layer and thus more carrier recombination occurs. Moreover, some of the acceptors are compensated by light-induced defects. The highly doped p-layer, however, does not cause much Voc degradation because the light-induced defects are negligible compared with the large number of doping-induced defects and acceptors. The experimental data show that the midgap defects induced by doping or light-soaking near the p/i interface cause the Voc limitation.