A new kind of polymeric semiconductor comprising a micrometer-sized assembly of alkylated-C(60) derivatives and carbon nanotubes is constructed in this work as an indicator of temperature rise resulting from the photothermal conversion of carbon nanotubes under near-infrared laser irradiation. Under such conditions, the local heating of this assembly in air reaches temperatures in excess of 220 degrees C, which would prove very useful for wide applications utilizing the photothermal properties of carbon nanotubes.