Realization of dual-heterojunction solar cells on ultra-thin ∼25 μm, flexible silicon substrates

Silicon heterojunction (HJ) solar cells with different rear passivation and contact designs were fabricated on ∼25 μm semiconductor-on-metal (SOM) exfoliated substrates. It was found that the performance of these cells is limited by recombination at the rear-surface. Employing the dual-HJ architecture resulted in the improvement of open-circuit voltage (V_oc) from 605 mV (single-HJ) to 645 mV with no front side intrinsic amorphous silicon (i-layer) passivation. Addition of un-optimized front side i-layer passivation resulted in further enhancement in V_oc to 662 mV. Pathways to achieving further improvement in the performance of HJ solar cells on ultra-thin SOM substrates are discussed.