19.2% Efficient InP Heterojunction Solar Cell with Electron-Selective TiO(2) Contact

[Image: see text] We demonstrate an InP heterojunction solar cell employing an ultrathin layer (∼10 nm) of amorphous TiO(2) deposited at 120 °C by atomic layer deposition as the transparent electron-selective contact. The TiO(2) film selectively extracts minority electrons from the conduction band of p-type InP while blocking the majority holes due to the large valence band offset, enabling a high maximum open-circuit voltage of 785 mV. A hydrogen plasma treatment of the InP surface drastically improves the long-wavelength response of the device, resulting in a high short-circuit current density of 30.5 mA/cm(2) and a high power conversion efficiency of 19.2%.