A GERMANIUM BACK-CONTACT TYPE CELL WITH IMPROVED EFFICIENCYFOR THERMO-PHOTOVOLTAICS

摘要

Reducing resistance loss for high current densities caused by high incident light energy is important inthermo-photovoltaic cells. In hope of resolving this problem, we propose a Ge back-contact type cell. This cell haswide grid contacts at the back instead of fine front grid contacts. Consequently, this structure is able to reduceresistance loss, and is suitable for thermo-photovoltaic applications. Calculated efficiency is in excess of 30% foremitted infrared light in thermo-photovoltaic applications. In experimental results, an efficiency of 6.0% forAM1.5G solar light was obtained, with an estimated efficiency of about 22% for infrared light, which corresponds toa selective emitter. To improve this efficiency, we developed a SiO2/SiNx anti-reflection coating to reduce bothreflection loss and recombination loss. We studied the light absorption rate, the passivation effect and the quantumefficiency of the high refractive index SiNx layers required for the coating. We clarified that a SiNx layer iseffective to achieve efficiency improvement in the Ge back-contact type cell.