Stability of ruthenium/organic dye co-sensitized solar cells: a joint experimental and computational investigation

Abstract

A joint experimental and theoretical study on the stability of dye-sensitized Solar Cells employing a mixture of black dye (N749) and Y1 organic coadsorbent is presented. The aim of the present work is to investigate the stability of these sensitizers, representing the efficiency state of the art in this field. Under the investigated conditions (1100h of ~1Sun light soaking at 55˚C) the co-sensitized device has shown a remarkable stability. The partial desorption of the organic co-adsorbent has been individuated as a possible cause for the slight reduction of the photocurrent value. Theoretical investigations through DFT methods on the dye-sensitized semiconductor surface, revealed a considerably lower adsorption energy for Y1 compared to N749, in particular upon oxidation, possibly leading to the dye desorption under working conditions. Coherently, devices employing only the Y1 organic dye have shown a considerably lower durability.

Role of co-sensitization in dye-sensitized and quantum dot-sensitized solar cells

“…It is important to note about the three important properties which are dependent on the anchoring group moieties. These properties include (a) electronic coupling between the dye and metal oxide photoanode, (b) orientation and packing of the adsorbed dye molecules and (c) long-term stability of the device [214,215]. Besides, the available anchoring site for the dye 2 depends upon the surface area of the TiO 2 nanoparticles.…”

“…For instance, it has been experimentally found that the binding of benzoic acid takes place through bidentate mode whereas for cyanoacrylic acid it's a tridentate mode [254]. These kind of different mode attachment of dyes also influenced by their geometrical parameters [214,215]. Each dye has some specific adsorption sites on the surface of the photoelectrode and hence there will be some available sites for the second dye adsorption.…”

“…Eventhough organic dyes are used for the co-sensitization process, their demerits such as aggregation on the TiO 2 Review SN Applied Sciences (2019) 1:186 | https://doi.org/10.1007/s42452-018-0054-3 [214,215]. The foremost advantages of QDs compared with organic dyes lead to several applications in solar cells.…”

Role of Co‐Sensitizers in Dye‐Sensitized Solar Cells

“…The IPCE spectrum of black dye+Y1 displayed broad absorption at wavelengths from 300 to 700 nm, leading to enhanced J SC of 20.88 mA cm −2 , whereas black dye+Y2 absorbed only in a narrow range of wavelengths from 350 to 420 nm. Thus, the PCE of black dye+Y1 improved up to 11.3 % when compared with the efficiency of black dye+Y2 . Additionally, the D–π–A architecture of Y3 co‐sensitized with ampiphilic Ru‐based dye (Amp Ru, Figure ) aids to reduce dye aggregation, charge recombination, and back‐electron transfer, thereby enhancing PCE (CR2 mechanism) .…”

“…Thus, the PCE of black dye + Y1 improved up to 11.3 %when compared with the efficiencyo fb lack dye + Y2. [51] Additionally,t he D-p-A architecture of Y3 co-sensitized with ampiphilic Ru-based dye (Amp Ru, Figure 2) aids to reduce dye aggregation, charge recombination, and back-electron transfer,t hereby enhancingP CE (CR2 mechanism). [52] The IPCE of Amp Ru + Y3 showeda bsorption band covering 300-800 nm, reaching am aximum of 80 %.…”