Fast Voltammetric and Electrochromic Response of Semiconductor Nanocrystal Thin Films

CdSe nanocrystal thin films exhibit stable and quantitative electrochemical responses when treated with cross-linking 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.