Three-Dimensional TiO₂/ZnO Hybrid Array as a Heterostructured Anode for Efficient Quantum-Dot-Sensitized Solar Cells

Abstract

The development of a novel nanoarray photoanode with a heterostructure on a transparent conducting oxide substrate provides a promising scheme to fabricate efficient energy conversion devices. Herein, we successfully synthesize the vertically aligned hierarchical TiO2 nanowire/ZnO nanorod or TiO2 nanowire/ZnO nanosheet hybrid arrays, which are proven to be excellent anode candidates for superior light utilization. Consequently, the quantum-dot-sensitized solar cells based on such hybrid arrays exhibit an impressive power conversion efficiency (PCE) under AM 1.5G one sun illumination with improved short-circuit current density (JSC) and fill factor compared to pristine TiO2 nanowire arrays. Combined with the chemical-bath-deposited Cu2S counter electrode, the eventual PCE can be further optimized to as high as 4.57% for CdS/CdSe co-sensitized quantum dot solar cells.

Quantum dot sensitized solar cell: Recent advances and future perspectives in photoanode

“…Recently Feng et al [93] have fabricated 3-D vertically aligned hierarchical structured photoanode consisting TiO 2 nano-wire and ZnO nano-wire or nano-sheet. The hybrid structures have shown high light harvesting capabilities due to larger surface area, more number of deposition sites for QD sensitizers.…”

Synthesis, properties, and applications of black titanium dioxide nanomaterials

“…Huang and co-workers [43,50] studied the electronic band structures of those doped TiO 2 nanomaterials by density functional theory, and explained the mechanism of the enhanced visible-light absorption. In addition, coupling with small-gap semiconductors (such as CdS and ZnO) or graphene have also been tried [58][59][60][61][62][63][64][65][66][67][68][69]. Oxygen vacancies and Ti 3+ can also been shown with visible-light activity [68,[70][71][72][73][74][75][76][77][78][79][80][81][82][83].…”

Zinc Oxide–Titania Heterojunction‐based Solid Nanospheres as Photoanodes for Electron‐Trapping in Dye‐Sensitized Solar Cells

“…Various architectures of both oxides, in the form of nanotubes, nanowires, clusters, hollow spheres, core–shell structures, and 3D hybrid arrays, have been explored for enhanced charge transport . Unfortunately, detrapping due to random electrical paths, surface states, and in some cases defects hinders their application in dye‐sensitized solar cells (DSSCs).…”

“…The electron transport in ZnO‐doped TiO 2 seems to be favorable, as seen from the lower electrode resistance (Figure c) and increase in the electron carrier density up to 47 % with increasing ZnO% (summarized in the Supporting Information, Table S1). The charge resistance at their interface ( R ct ) increases with increasing ZnO, however the value for 1 % ZnO is comparatively minimal (∼13.88 Ω) as derived from the second semicircle and by fitting a Nyquist plot with equivalent circuit as shown in Figure c. Because the conduction band of ZnO formed by the s orbital provides a significantly smaller μ e (effective electron mass) compared to the higher μ e corresponding to the d orbital of TiO 2 conduction band, ZnO‐doped TiO 2 has more electron mobility than TiO 2 . The enhancement in electron transport (ca.…”