Double-heterojunction crystalline silicon solar cell fabricated at 250°C with 12.9 % efficiency

Double-heterojunction crystalline silicon solar cells were fabricated at temperatures of <250°C using Si/organic and Si/metal-oxide heterojunctions, but no p-n junction in silicon. The first heterojunction, formed by spin-coating organic PEDOT:PSS on n-type silicon, functions as a front surface field that separates the photogenerated carriers and blocks electron dark-current while allowing hole photo-current to pass though. The second heterojunction, formed via metal-organic chemical vapor deposition of titanium dioxide on n-type silicon, functions as a back surface field that reduces hole dark-current while allowing electron photocurrent to pass through. Compared to a single heterojunction solar cell with only a Si/PEDOT heterojunction, the double-heterojunction device is more efficient with a power conversion efficiency of 12.9% under AM1.5.