Polyethylene glycol (PEG)-based solid-solid phase change materials (SSPCMs) were first synthesized using PEG and hexamethylene diisocyanate trimer (HDIT) via one-step and solvent-free approach. When HDIT content is 5 wt %, the obtained SSPCM has no leakage at 80 degrees C which is higher than the melting temperature of PEG, the phase change temperatures, maximum latent heat and relative enthalpy efficiency of the obtained SSPCM are 65 degrees C, 136.8 J/g and 87.1%, respectively. After 200 thermal cycles, the latent heat remains nearly constant. It proves that the fabricated SSPCMs has good thermal reliability and reusability. At the same time, the SSPCMs own excellent light-thermal conversion performance and good thermal stability in a broad temperature range of applications. All the above results show that the obtained SSPCMs own great potential as direct solar light absorber for solar thermal energy storage.