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

TiO 2 nanoparticles (NP) at top of TiO 2 nanotube (TiO 2 NP@TiO 2 NT) double-layered architecture is constructed to combine the advantages of TiO 2 NP and TiO 2 NT together. This composite TiO 2 NP@TiO 2 NT 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 TiO 2 NP@TiO 2 NT have been investigated in contrast with bare TiO 2 NP and bare TiO 2 NT architectures with almost the same thickness. The results show that the power conversion efficiency (PCE) of QDSSCs could be enhanced using TiO 2 NP@TiO 2 NT and improved to 3.26%, which is 80% and 38% higher than QDSSCs based on bare TiO 2 NT and bare TiO 2 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 TiO 2 NP@TiO 2 NT can combine advantages of TiO 2 NP and TiO 2 NT structures together and lead to a higher light harvesting efficiency, electron collecting efficiency, and efficient electron transport.