Patent ID: 7081368

Claim:
A gas sensing method for sensing a gas to be sensed using a sandwich cell formed by sandwiching a photoconductive organic semiconductor layer between two metallic electrodes, the sandwich cell exhibiting a photocurrent multiplication phenomenon that a photocurrent occurring in the photoconductive organic semiconductor layer in response to light irradiation under application of a voltage by the electrodes is multiplied, the method comprising the steps of: (A) a step of irradiating the organic semiconductor layer with light in the condition that a voltage is applied on the organic semiconductor layer by the electrodes, thereby causing a multiplied photocurrent to generate at an organic/metallic interface, the voltage having such a magnitude that allows a photocurrent to flow between the electrodes in a quantum yield of not less than 1 when the organic semiconductor layer is irradiated with light; (B) a step of bringing the gas to be sensed into contact with the organic/metallic interface where photocurrent multiplication is occurring, in the condition of(A); and (C) a step of measuring a photocurrent flowing in the organic semiconductor layer to sense gas on the basis of a change in photocurrent associated with the contact of the gas to be sensed.