High-efficiency inverted solar cells based on a low bandgap polymer with excellent air stability

A high-efficiency inverted bulk heterojunction (BHJ) solar cell with good air stability is fabricated using annealing-free ZnO nanocrystals as an electron-transport layer and a blend of a low bandgap polymer PDTSTPD and PC71BM as an active layer. A power conversion efficiency as high as 6.7% has been achieved on the inverted devices with an active area of 1.0 cm2 using nitrobenzene as a processing additive. The device is highly stable, retaining 85% of its original efficiency after being stored in air for 32 days even without encapsulation.

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► A high-efficiency inverted BHJ solar cell is fabricated from a low bandgap polymer.
► Annealing-free ZnO nanocrystals are used as an electron-transport layer.
► An efficiency of 6.7% is achieved with nitrobenzene as a processing additive.
► 91% of the original efficiency is retained after being stored in air for two weeks.