Assessing TiOx as a hole-selective contact for silicon heterojunction solar cells

Transparent materials with tunable work functions are attractive for carrier-selective contacts with minimal current loss caused by parasitic absorption. We investigate the viability of TiOx, deposited using a novel aerosol-based tool, as a wide-bandgap hole-selective contact to replace p-type amorphous silicon in silicon heterojunction solar cells. Cells with a TiOx hole contact and no intrinsic amorphous silicon passivation layer achieve contact resistivities as low as 0.1 Ω∙cm
²
but have low implied open-circuit voltages, resulting in cell efficiencies as high as 14.7%. Including the passivation layer increases the implied open-circuit voltage to above 720 mV but markedly reduces the contact’s selectivity.