ELECTROCHEMILUMINESCENCE FROM CALIXARENE-COATED POROUS SI LIQUID-JUNCTION CELLS

In this paper, the electrochemiluminescence (ECL) of calixarene carbox ylic acid coated porous Si (PS) is reported. Electrochemiluminescence is observed from the anodic oxidation of calixarene-coated porous Si i n an electrolyte containing 1.0 M H2SO4 These calixarene carboxylic ac id derivatives coated onto the porous Si surface affect both the durat ion and efficiency of the light emission. Electrochemiluminescence can be generated for longer periods of time for these coated porous Si ju nctions relative to untreated porous Si, ranging from up to 3 h for ca lix[4]arene-coated porous Si to about 50 min for the calix[n]arene (it = 5, 7, 8) derivatives. This improved duration of electrochemilumines cence comes at the cost of quantum efficiency; for calix[8]arene-coate d PS it is 0.0015%, while for calix[4]arene-coated porous Si, <0.001%. The electrochemiluminescence peak maximum is red-shifted beyond 700 n m with continued bias. These observations are attributed to packing di fferences between different calixarene carboxylic acid derivatives as thin films and subsequent bias-induced Si nanoparticle oxidation in th e porous matrix.