Construction of TiO2 NP@TiO2 NT double-layered structural photoanode to enhance photovoltaic performance of CdSe/CdS quantum dots sensitized solar cells

Abstract

TiO2 nanoparticles (NP) at top of TiO2 nanotube (TiO2 NP@TiO2NT) double-layered architecture is constructed to combine the advantages of TiO2 NP and TiO2 NT together. This composite TiO2 NP@TiO2NT architecture as photoanode possesses a larger surface area for more QDs loading, and highly tubular structure for electron swift transport. Based on this architecture, CdSe/CdS quantum dots (QDs) have been successfully synthesized by successive ionic layer adsorption reaction (SILAR) method for quantum dots-sensitized solar cell application. The photovoltaic performance of QDSSCs based on TiO2 NP@TiO2 NT have been investigated in contrast with bare TiO2 NP and bare TiO2 NT architectures with almost the same thickness. The results show that the power conversion efficiency (PCE) of QDSSCs could be enhanced using TiO2 NP@TiO2 NT and improved to 3.26%, which is 80% and 38% higher than QDSSCs based on bare TiO2 NT and bare TiO2 NP, respectively. The BET surface area, UV–vis absorption spectra, and incident photon to current conversion efficiency (IPCE) measurements results show the evidence that the TiO2 NP@TiO2 NT can combine advantages of TiO2 NP and TiO2 NT structures together and lead to a higher light harvesting efficiency, electron collecting efficiency, and efficient electron transport.