Coral-Like CoSe2-Nitrogen-Doped Porous Carbon as Efficient Counter Electrodes for Quantum Dot Sensitized Solar Cells

Exploration of counter electrode (CE) catalysts with excellent reduction activity to S n 2− and low charge transfer resistance ( R ct ) is always a major challenge for the development of quantum dot sensitized solar cells. In this work, coral-like CoSe 2 - nitrogen-doped porous carbon hydrides (CoSe 2 -NC) were successfully prepared by two-step calcination of zeolitic imidazolate framework (ZIF), including carbonization and selenization process. Scanning electron microscopy shows that the CoSe 2 -NC catalyst presents a coral-like microscopic morphology composed of nanospheres. Electrochemical impedance spectroscopy displays that the CoSe 2 -NC CE presents a low R ct of 1.04 Ω. The PCE of the QDSSC based CoSe 2 -NC CE is up to 5.06%which is 26%, 87% higher than those of CoSe 2 and NC CEs. The enhanced photovoltaic performance is attributed to the unique coral-like structure and the synergistic catalytic effect of CoSe 2 and NC.