Double-heterojunction crystalline silicon solar cell with electron-selective TiO2 cathode contact fabricated at 100?C with open-circuit voltage of 640 mV

A double-heterojunction c-Si solar cell was fabricated at maximum process temperature of 100°C. We demonstrate an electron-selective passivated contact to Si using TiO₂, which increased the open-circuit voltage by 45 mV compared to a device with a direct metal to n-type substrate contact. In the fabricated structure, PEDOT/Si replaced the front-side p-n junction of conventional Si-based solar cells while the Si/TiO₂ interface is formed on the back-side. Compared to previous work [1], the V_oc has increased from 620 to 640 mV while maintaining a maximum process temperature of 100°C. Critical to the improved performance is better passivation of the Si/TiO₂ interface. The increase in V_oc can be attributed to an interface recombination velocity of ~75 cm/s, which is consistent with photoconductance decay measurements.