Industrial type passivation on interdigitated back junction solar cells

Interdigitated Back Junction (IBJ) solar cells are suited to be realized on thin wafers, since they need a combination of high diffusion lengths and thin substrates. Here we present an industrial type passivation stack at the rear surface of an IBJ solar cell, consisting of a low quality SiO₂ and a SiN_x layer, which has proven its value in the i-PERC concept developed at IMEC. Quasi-Steady-State Photo Conductance (QSSPC) lifetime measurements indicate an improvement of lifetime from 10¿s to 180¿s after application and rapid thermal processing (RTP) of the industrial passivation stack. For the IBJ solar cell concept without back surface field (BSF); this results in an absolute increase in energy conversion efficiency of 2% absolute, going from 14% to 16% and with a BSF up to 18%. Out of the presented cell data we can conclude the excellent passivation quality of the applied industrial passivation stack.