Co-sensitization effect of N719 dye with Cu doped CdS colloidal nanoparticles for dye sensitized solar cells

Dye-sensitized solar cell's (DSSC) performances are enhanced by engineering the materials at the interface of various device components owing to easy and inexpensive fabrication steps. Ru (II) polypyridyl-based synthetic dyes are the most widely used photosensitizers for DSSCs due to their superior molar extinction coefficient and facile interaction with metal oxide electrodes. However, these dyes are mostly expensive, and as a result, natural dyes and metal-free organic dyes have become an alternative way for sensitization to reduce the significant drawbacks of synthetic dyes. In this study, minimizing the usage of the N719 dye can be performed through an alternative method for better light-harvesting through supreme optical interfacial interaction with colloidal Cu-doped CdS as a co-sensitizer in a facile approach. This co-sensitization signifies the colloidal CdS (donor), which can corroborate the energy transfer mechanism with the N719 dye (acceptor). The introduction of Cu causes extreme tuning of broad absorption to near-infrared for CdS, enhancing the solar light harvesting entrapment followed by extensive optical interaction with N719 dye. This accelerates the activity of the sensitizers for light absorption enhancement and expects a better performance of DSSC compared to traditional sensitization. A massive improvement in photocurrent density (∼42 %) was observed without sacrificing other photovoltaic parameters, as observed for TiO ₂-based photoanodes. The sensitizer's interfacial optical energy transfer process, unless excited electron recombination, may indirectly be used as an excitation source of the acceptor and minimizes the recombination energy loss.