ABSTRACTAs an alternative to crystalline silicon or thin film solar cells on rigid glass substrates, we aim to fabricate amorphous silicon (a-Si)/nanocrystalline silicon (nc-Si) tandem thin film solar cells on cheap flexible substrates. We have chosen polycarbonate as the superstrate and adapted the a-Si and nc-Si deposition processes for deposition at a maximum temperature of 130°. Because a-Si deposited at low temperatures has a high band gap, we were able to fabricate very thin (<1.2 μm) a-Si/nc-Si solar cells, because the high band gap of the a-Si shifts the current generation more towards the bottom cell, allowing for a much thinner (900 nm) bottom cell. The somewhat lower Jsc of the complete cell is partly compensated by a higher Vocwhich results in an initial conversion efficiency of 9.5% for the low temperature tandem solar cells on glass.
Wide band gap kesterite absorbers for thin film solar cells: potential and challenges for their deployment in tandem devices
