Enhanced anodic electrochemiluminescence due to efficient exchange recombination and its sensing application
To obtain semiconductor nanocrystals (NCs) with strong anodic electrochemiluminescence (ECL) remains a challenge due to their insufficiency to resist following corrosion upon holes injection to the NCs. Herein, we report strong and stable anodic ECL generated from 0.8 at% Mn 2+ doped CdS NC films on indium tin oxide (ITO) electrode in the presence of coreactant triethanolamine (TEOA) under potential scan to +1.5 V vs. saturated calomel electrode (SCE), which is much more negative than the valence band potential of host NCs. The Mn 2+ doping leads to an 8-fold enhancement in anodic ECL intensity in comparison with undoped CdS NC films due to efficient Mn excitation via nonradiative recombination energy transfer, i.e., exchange recombination. The efficiency is dependent on Mn 2+ doping amount as well as applied potential for holes injection with the maximum obtained when the charge transfer to Mn dopants is possible and the energy gap between conduction band and applied potential matches with Mn excitation. This anodic ECL was used to detect dopamine, a model analyte, showing a wide linear range from 5 nM to 1 μM with a detection limit of 1 nM at S/N=3. This work provides a new insight into ECL generation in doped semiconductor NCs. The Mn 2+ doped CdS NCs passivated by carboxylic groups display great potential in future development of biosensors .
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