Composites prepared by grafting poly(3-hexylthiophene) (P3HT) onto the surfaces of reduced graphene oxide (RGO) (RGO-g-P3HT) exhibit an enhanced photothermal effect due to photoinduced energy transfer from P3HT to RGO. A remote photo-controlled electrical switch was prepared using RGO-g-P3HT as a photothermal layer.