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 Sn2− and low charge transfer resistance (Rct) is always a major challenge for the development of quantum dot sensitized solar cells. In this work, coral-like CoSe2 - nitrogen-doped porous carbon hydrides (CoSe2-NC) were successfully prepared by two-step calcination of zeolitic imidazolate framework (ZIF), including carbonization and selenization process. Scanning electron microscopy shows that the CoSe2-NC catalyst presents a coral-like microscopic morphology composed of nanospheres. Electrochemical impedance spectroscopy displays that the CoSe2-NC CE presents a low Rct of 1.04 Ω. The PCE of the QDSSC based CoSe2-NC CE is up to 5.06%，which is 26%, 87% higher than those of CoSe2 and NC CEs. The enhanced photovoltaic performance is attributed to the unique coral-like structure and the synergistic catalytic effect of CoSe2 and NC.