Improved photovoltaic performance of solar cells co-sensitized with graphitic C3N4 and CdS quantum dots

Abstract

In this work, C3N4 in graphite-like layer structure (graphitic C3N4, g-C3N4) prepared from melamine was applied into quantum dot-sensitized solar cells (QDSCs) as the co-sensitizer of CdS quantum dots (QDs). In the as-prepared photoanodes, g-C3N4 could improve the visible-light absorption and play a supporting role to improve the stability of TiO2 photoanode microstructure simultaneously. Through modifying the content of g-C3N4 in TiO2 photoanode, QDSCs based on 10 wt% g-C3N4 in TiO2 photoanode achieved the most optimal photovoltaic performance. Its short-circuit current density (Jsc) improved greatly, up to 14.08 mA/cm2, 72.5% higher than that of QDSCs without g-C3N4 and furthermore, the power conversion efficiency (PCE) was 4.65% with an increase of 106.7%. The mechanism of effect of g-C3N4 content on the photovoltaic performance of QDSC is investigated systematically through combining photoanodes microstructure characterization with electrochemical impedance (EIS) and current–voltage (J–V) curves analysis of cell samples.