A novel structure, high conversion efficiency p‐SiC/graded p‐SiC/i‐Si‐Si/metal substrate‐type amorphous silicon solar cell

摘要

A novel structure, high conversion efficiency amorphous silicon (a‐Si)/metal substrate‐type solar cell has been developed. The new structure, deduced from the conventional pin junction by the use of a gradual compositional grading p‐type a‐SiC:H layer between an ultrathin (∼20 Å) wide optical band gap (∼2.4 eV) p‐type a‐SiC:H layer and the i layer, exhibits markedly enhanced open‐circuit voltage (Voc) and short‐circuit current density (Isc) over the conventional a‐Si pin/substrate‐type solar cell. Especially, the collection efficiency in the newly developed structure was found to be remarkably increased at short wavelengths. The experimentally observed improvement in the blue response is due to the reduction in effective interface recombination combined with the enhanced window effect. An energy conversion efficiency of 8.40% under air mass (AM) 1 (100 mW/cm2) illumination has been obtained in the first trial of a cell fabricated by the rf glow discharge decomposition of pure silane (SiH4).