Near infrared electrochromism of lutetium phthalocyanine

The near infrared (NIR) electrochromism of lutetium phthalocyanine (LuPc2) is studied both in its solution and vacuum deposited thin film. The LuPc2 in neutral state has near infrared absorption in the region from 1100 nm to 1600 nm. In electrochemical oxidized state (+1.0 V), it has an absorption peak at 880 nm. In electrochemical reduced state (−1.0 V), it shows no absorption in the near IR region. The attenuation at 1300 nm of electrochromic (EC) devices based on solution and thin film of LuPC2 was also studied. Attenuation of 0.31 dB and 0.28 dB was achieved respectively and the response time was 24 s and 1 s, respectively. These results demonstrate that LuPc2 is a kind of NIR EC material and it has potential application for variable optical attenuator.