Chemically converted graphene–room temperature ionic liquid (CCG–RTIL) porous materials were prepared by electrochemical reducing graphene oxide followed by solvent exchange. The resulted CCG–RTIL materials possess 3D porous structure with textured surface, and show good stability in air. Under laser irradiation the temperature of CCG–RTIL materials increased rapidly and significantly, indicating the high photothermal conversion ability of these materials. The influence of CCG–RTIL thickness on the photothermal conversion performance was investigated. These CCG–RTIL materials were used as light absorbers to modify thermoelectric devices, forming light-driven thermoelectric generators, and significantly enhanced the performance of these devices. This work suggests that CCG–RTIL porous materials prepared by this electrochemical method are promising light absorbers for solar electric generation and other photo-thermo-electric conversion devices.