White light electroluminescence from PSi devices capped with poly(thiophene)(s) as top contact

For the first time, electrochemically deposited poly(3-methylthiophene) and chemically produced poly(3-methylthiophene) and poly(3-phenoxymethylthiophene) have been employed as top electrical contact on porous silicon light-emitting devices. The polymer-capped devices emitted white light as opposed to the uncapped devices, which emitted orange colour. The polymer-capped devices show much higher rectification ratio (up to 1×10⁵) as opposed to 1×10³ for the uncapped devices at ±10 V. The polymer-capped devices show 10³–10⁴-fold improvement in the luminous efficiency over the uncapped devices. Electrochemically deposited poly(3-methylthiophene) top contacts give a luminous efficiency of 8×10⁻⁵ lm W⁻¹ as opposed to 3×10⁻⁹ lm W⁻¹ obtained from uncapped devices. All the devices were found to fit the space charge limited current model.