Rapid thermal annealing assisted facile solution method for tungsten-doped vanadium dioxide thin films on glass substrate

Vanadium dioxide VO2 is an important thermochromic material with useful applications in smart energy devices. This paper describes the synthesis of high-quality vanadium dioxide thermochromic thin films directly on glass substrate without any barrier layer prepared using a simple solution method. We demonstrate that 50 nm thick VO2 films display excellent visible transmittance (76.9% on glass, 69.4% on fused silica) and a large NIR switching efficiency (33.8% on glass, 44.3% on fused silica) at 1600 nm. It is found that the metal to semiconductor phase transition temperature Tc of undoped films can be reduced from a theoretical value of 68 °C to 49.4 °C by rapid thermal annealing. With W doping a continuous drop in the Tc is observed and for VO2 with 2% W doping, a Tc of 25.8 °C is achieved. These good optical properties and the near room-temperature phase transition temperature suggest that solution processing with the rapid thermal annealing process is a feasible method to obtain this promising material on glass substrate for practical application in thermochromic smart windows. •VO2 thin films deposited by sol-gel method on glass and fused silica substrates using VO(acac)2 as the precursor.•VO2 on different substrates after rapid thermal annealing have lower phase transition temperatures and good solar modulation .•VO2 doped with 2% W deposited on glass exhibits phase transition at room temperature.