Fast voltammetric and electrochromic response of semiconductor nanocrystal thin films

CdSe nanocrystal thin films exhibit stable and quantitative electrochemical responses when treated with crosslinking molecules such as dithiols or diamines. For the first time, a voltammetric response is recorded for the reduction of the nanocrystals with quantitative injection of electrons in the 1S(e) state. Injection in the 1P(e) manifold is also achieved as evidenced by spectroscopic measurements. For a 100 nm thick film of 6.2 nm diameter nanocrystals, electrochromic changes are on 100 ms time scales, and remain robust after 10 000 cycles.