Exploring the photo paper as flexible substrate for fabrication of a-Si:H based thin film solar cells at low temperature (110 °C): Influence of radio frequency power on opto-electronic properties

The effect of variation of radio frequency (rf) power on the structural, optical and electronic properties of intrinsic hydrogenated amorphous silicon (a-Si:H) films deposited at very low substrate temperature (Ts) 110 °C were studied. These films were prepared varying rf power (40-70 W) on borosilicate glass, photo paper and c-Si substrates using rf-plasma enhanced chemical vapour deposition (13.56 MHz) technique. All films show amorphous structure confirmed by Raman measurement and also supported by spectroscopic ellipsometry (SE) measurements. SE results show that at higher rf power, amplitude of peak decreases and broadening increases due to increase in void density. Intrinsic layer with optimized rf power was used for fabricating n-i-p solar cell on flexible polyethylene terephthalate (PET), polyimide (PI), photo paper and rigid glass. The efficiency of solar cells fabricated on flexible PET and PI is 3.30% and 3.36%, which is close to 3.82% on rigid glass. In case of solar cells on photo paper, an efficiency of ~ 1.08% was obtained. The studies show that it is possible to fabricate a-Si:H based solar cells on photo paper and other substrates at very low Ts.