Observation of photo-induced insulator-to-metal transition in charge-ordered α-(BEDT-TTF)2I3 thin crystal by simultaneous transport and optical measurement

► We observed photo-induced insulator-to-metal transition in an α-(BEDT-TTF)2I3 thin crystal. ► We simultaneously evaluated conductance and transmittance in the photo-induced metallic state. ► The photo-induced metallic phase is charge order melting state caused by cooperative effect. ► The photo-induced metallic phase inhomogeneously grows.