Dye-sensitized near-infrared room-temperature photovoltaic photon detectors

Dye molecules bonded to a semiconductor surface could inject carriers to a band on photoexcitation. This process known as dye-sensitization is used for extending the sensitivity of silver halide emulsions. More recently, dye-sensitization has been adopted to devise solar cells. A near-infrared (NIR) sensitive heterojunction n-TiO2∕D∕p-CuSCN (where D denotes a NIR absorbing dye) is developed to examine the possibility of using dye-sensitization for IR detection. Although the responsivity is lower and response slow compared to silicon detectors, dye-sensitized detectors would be cost effective, especially for large area devices. They are operable at room temperature and have the advantage of insensitivity to noise induced by band-gap excitations (providing high specific detectivity of ∼1011). Furthermore, the spectral response can be adjusted by choosing the appropriate dye.