Realizing high photothermal conversion efficiency in traditional Chinese purple (BaCuSi 2 O 6 ) pigment

Abstract Chinese purple (CP), an ancient traditional pigment, represents the rich cultural and scientific heritage of an ancient civilization. To achieve high‐purity CP pigment in a more economical and efficient manner, we synthesized CP using a low‐temperature hydrothermal route. Interestingly, we observed the emergence of an emission peak at 894 nm in CP under irradiation at λ ex  = 650 nm. Additionally, it was noted that the CP powder exhibited a significant photothermal effect when exposed to near‐infrared light irradiation. A photothermal conversion efficiency of 19% was achieved in the CP pigment. This study not only sheds light on the enigmatic nature of this ancient pigment but also highlights its potential as a critical photothermal conversion material.