Photothermal therapy (PTT), as a new type of tumor treatment technology, has received intensive attention recently due to its high efficiency for tumor inhibition and low damage to normal tissue. Over the past decade, many photothermal conversion agents have been widely used in the research of PTT, especially inorganic nanomaterials with surface plasmon resonance properties, such as gold based nanoparticles. With the development of nanotechnology and nanomaterials, the types and properties of photothermal agents have been increasingly improved. Spired by the excellent cancer therapy effect of photothermal therapy, people pay more attention to the possibility of its clinical application. In recent years, organic photothermal agents have been developed rapidly, due to their abilities to overcome the non-biodegradable characteristics of inorganic materials. This article summarizes the recently developed research of several typical photothermal nanomaterials, including small molecular dyes, supramolecular complexes and conjugated polymers. Based on these organic agents, various biocompatible materials are developed for clinical photothermal therapy. And the application of the imaging guided photothermal therapy and combined therapy is briefly described. In the end, the primary categories and development direction of organic photothermal agents are summarized. And the problems and challenges of clinical photothermal therapy are pointed out.

Contents
1 Introduction
2 Small molecular dyes
2.1 Indocyanine green
2.2 Prussian blue
2.3 Thiadiazole derivatives
3 Supramolecular complexes
3.1 Porphysomes
3.2 BPDI/(CB[7])₂
4 Conjugated polymers
4.1 Polyaniline
4.2 Polypyrrole
4.3 PEDOT:PSS
4.4 Polydopamine
5 Other applications of photothermal therapy
5.1 Imaging-guided photothermal therapy
5.2 Combined cancer therapy
6 Conclusion and outlook