Hierarchically Structured ZnO Nanorods as an Efficient Photoanode for Dye‐Sensitized Solar Cells

Abstract

Hierarchical ZnO nanorods composed of interconnected nanoparticles, which were synthesized by controlling precursor concentrations in a solvothermally assisted process, were exploited as photoanodes in dye-sensitized solar cells (DSCs). The as-prepared hierarchical nanorods showed greatly enhanced light scattering compared to ZnO nanoparticles for boosting light harvesting while maintaining sufficient dye-adsorption capability. The charge-transfer characteristics were studied by electrochemical impedance measurements, and reduced electron recombination and longer electron lifetime were observed for the ZnO nanorods. Photovoltaic characterization demonstrated that DSCs utilizing the hierarchical nanorods significantly improved the overall conversion efficiency by 34 % compared to nanoparticle-based DSCs.

Recent advances in photo-anode for dye-sensitized solar cells: a review

“…Efficiency enhancement from 3.08 to 4.13% was reported by Peng et al by replacing ZnO nanoparticles with ZnO hierarchical nanorods as DSSC photo‐anode. This was attributed to significantly enhanced light scattering of ZnO nanorods compared with ZnO nanoparticle, which led to efficient light harvesting . Longer electron lifetime and reduced electron recombination of ZnO nanorods were verified from EIS measurement as well.…”

“…ZnO nanowire also demonstrates several interesting properties such as antireflective and light‐trapping properties, enhanced surface area and solution processabilty as reported in literature . Besides, 1D nanostructures with large sizes can enhance the LHE due to their superior light‐scattering ability . However, 1D ZnO nanostructures have limited surface area, which inevitably lead to inferior J sc due to lower dye adsorption .…”

High‐Efficiency Dye‐Sensitized Solar Cells Based on a ZnO Nanorod/ Nanosheet Hierarchical Structure

“…Up to now,v arious hierarchical structures based on ZnO NRs have been fabricated, such as the ZnO NRs/NPs, [12,13] the ZnO NRs/NRs, [14][15][16][17] andt he ZnO NRs/NSs, [18] and the purpose of fabricating the hierarchically structured film based on ZnO NRs is to retain the rapid electron transport property of the ZnO NRs while ensuringar elatively large specific surface area to increase the absorption of dye.T he hierarchically structured films of ZnO NRs/NRs still have a relatively small specific surface area and only absorb small amountso fd ye,r esulting in ar elatively low PCE of the cells. Forh ierarchically structured films of ZnO NRs/NPs,t he 3D ZnO NPs have ar elatively large specific area.…”

Full Solution‐Processed Synthesis and Mechanisms of a Recyclable and Bifunctional Au/ZnO Plasmonic Platform for Enhanced UV/Vis Photocatalysis and Optical Properties

“…Ad irect gap of 3.37 eV and large exciton binding energy (60 meV) makes it one of the most promising materials for light-emittingd evices, sensing, and nanostructure devices. [3,4,5] Superhydrophobic surfaces of ZnO have been recently demonstrated. [6] By sharing similar photocatalytic mechanisms with more popular TiO 2 ,Z nO also shows huge po-tentiali nt he photodegradation of environmental pollutants and photoelectrochemical water splitting.…”

“…ZnO is a versatile wide‐band‐gap II‐VI semiconductor with wurtzite crystal structure. A direct gap of 3.37 eV and large exciton binding energy (60 meV) makes it one of the most promising materials for light‐emitting devices, sensing, and nanostructure devices . Superhydrophobic surfaces of ZnO have been recently demonstrated .…”