Low temperature deposition of high open-circuit voltage (>1.0 V) p–i–n type amorphous silicon solar cells

P–i–n type hydrogenated amorphous silicon (a-Si:H) solar cells were deposited by the radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) process at a low substrate temperature of 125 °C, which is compatible with low-cost poly (ethylene terephthalate) (PET) plastic substrates. Wide band gap (Eopt>1.88 eV) intrinsic a-Si:H films were achieved before the onset of the microcrystalline regime by changing the hydrogen dilution ratios. On the other hand, the structural, optical and electrical properties of p-type hydrogenated amorphous silicon carbide (p-a-SiC:H) window layers have been optimized at 125 °C. High quality p-a-SiC:H film with high optical band gap (E04=2.02 eV) and high conductivity (σd=1.0×10−7 S/cm) was deposited at ‘low-power regime’ under low silane flow rates and high H2 dilution conditions. With the combination of wide band gap p-a-SiC:H window layers and intrinsic a-Si:H layers, a high Voc of 1.01 V (efficiency=5.51%, FF=0.72, Jsc=7.58 mA/cm2) was obtained for single junction a-Si:H p–i–n solar cell at a low temperature of 125 °C. Finally, flexible a-Si:H solar cell on PET substrate with efficiency of 4.60% (Voc=0.98 V, FF=0.69, Jsc=6.82 mA/cm2) was obtained.