Electrochemically Deposited NiO Films as a Blocking Layer in p-Type Dye-Sensitized Solar Cells with an Impressive 45% Fill Factor

Abstract

The enhancement of photoelectrochemical conversion efficiency of p-type dye-sensitized solar cells (p-DSSCs) is necessary to build up effective tandem devices in which both anode and cathode are photoactive. The efficiency of a p-type device (2.5%) is roughly one order of magnitude lower than the n-type counterparts (13.1%), thus limiting the overall efficiency of the tandem cell, especially in terms of powered current density. This is mainly due to the recombination reaction that occurs especially at the photocathode (or Indium-doped Tin Oxide (ITO))/electrolyte interface. To minimize this phenomenon, a widely employed strategy is to deposit a compact film of NiO (acting as a blocking electrode) beneath the porous electrode. Here, we propose electrodeposition as a cheap, easy scalable and environmental-friendly approach to deposit nanometric films directly on ITO glass. The results are compared to a blocking layer made by means of sol-gel technique. Cells embodying a blocking layer substantially outperformed the reference device. Among them, BL_1.10V shows the best photoconversion efficiency (0.166%) and one of the highest values of fill factor (approaching 46%) ever reported. This is mainly due to an optimized surface roughness of the blocking layer assuring a good deposition of the porous layer. The effectiveness of the implementation of the blocking layer is further proved by means of Electrochemical Impedance Spectroscopy.

Fabrication of copper‐niobium‐oxygen complexes as a photocathode for p‐type dye‐sensitized solar cell

“…These free moving electrons face a delay of the charge transport between the particle leading to FTO 53,54 . The iodide electrolyte and the N719 dye favor the recombination process, which affects the charge injection and collection efficiency 55,56 . For the commercialization of the fabricated cell, a detailed investigation on the interfacial contacts and interfacial contacts will be done in our upcoming works.…”

Hierarchical NiO/CMK-3 Photocathode for a p-Type Dye-Sensitized Solar Cell with Improved Photoelectrochemical Performance and Fast Hole Transfer

“…A compact NiO blocking layer was first deposited on fluorine-doped tin oxide (FTO) glass, and then a hierarchical NiO/CMK-3 or NiO-clusters layer was applied. A compact NiO blocking layer can effectively improve the overall photoelectrical performance (for example, short circuit current density: J sc , open circuit voltage: V oc , fill factor: FF and photovoltaic conversion efficiency: η), and suppress hole transfer recombination, so as to increase hole collection efficiency [2,11,34]. The device based on hierarchical NiO/CMK-3 shows a higher J sc (5.25 mA cm -2 ) than that based on NiO clusters (2.86 mA cm -2 ).…”

“…They are caused by (i) the fast charge recombination between the redox mediator dye and holes generated in the NiO and (ii) the overall low light-harvesting efficiency [7,8]. It is believed that the nature and morphology of nanocrystalline NiO has a great influence on the hole transfer processes that occur in the semiconductor electrode [9][10][11][12][13][14]. Although NiO nanoparticles were viewed as a promising material for p-DSSCs, they cannot fulfill all of the requirements for the target application.…”

Efficiency Boost in Dye-Sensitized Solar Cells by Post- Annealing UV-Ozone Treatment of TiO2 Mesoporous Layer

“…Thus, there are many scientific papers focused on changing the original materials used by Grätzel ( Figure 1 a) or modifying them. The mesoporous titanium(IV) oxide layer used originally as a photoanode was exchanged by zinc oxide [ 7 , 8 ] and nickel(II) oxide [ 9 ] nanoparticles or doped with tungsten [ 10 ], sulfur [ 11 ] or copper [ 12 ]. Platinum nanoparticles forming the counter electrode were successfully replaced [ 13 ] by e.g., carbon [ 14 ], tungsten disulfide [ 15 ], or molybdenum oxide [ 16 ].…”