Inhibiting Interfacial Recombination Events in Dye-Sensitized Solar Cells using Self-Assembled Bilayers

Abstract

The rate and efficiency of electron transfer events at the semiconductor-dye-electrolyte interface is of critical importance to the overall performance of dye-sensitized solar cells (DSSCs) and dye-sensitized photoelectrosynthesis cells. In this work, we introduce self-assembled bilayers composed of a metal oxide electrode, bridging molecules, linking ions, and dye as an effective strategy to manipulate interfacial electron transfer events at the photoanode of DSSCs. Spectroelectrochemical measurements including current-voltage, incident photon-to-current efficiency, and electrochemical impedance spectroscopy are used to quantify interfacial electron transfer and transport events with respect to the length of the bridging molecules. The general trend in increased lifetime and diffusion length in TiO2 as well as an increase in open circuit voltage with bridge length indicate that the bilayer is an effective strategy in inhibiting the TiO2(e(-)) to redox mediator recombination events. However, the increased separation between the dye and the semiconductor also reduces the electron injection rate resulting in a decrease in photocurrent as the bridge length increases. The observed enhancement in open circuit voltages are far outweighed by the significant decrease in photocurrent and thus overall device performance decreases with increasing bridge length.

Influence of the electron buffer layer on the photovoltaic performance of planar Sb2(SxSe1‐x)3 solar cells

“…Thus, R rec follows the same trend as V oc (see Figure B and Table ). This observation is in accordance with the well‐known phenomenon that lower R rec leads to a decrease in V oc , as well as differences in the density of trap states expected at the 3 interfaces. The agreement between the trends of recombination rates and TSPV measurements requires the compensation of C μ and R rec , since the recombination of photo‐generated carriers is inversely proportional to the product of R rec C μ .…”

“…Thus, R rec follows the same trend as V oc (see Figure 4B and Table 2). This observation is in accordance with the well-known phenomenon that lower R rec leads to a decrease in V oc , 39 interfaces. Energy-dispersive X-ray spectroscopy spectra shown in Figure S10 indicate Cd-diffusion into Sb 2 (S x Se 1-x ) 3 films similar to that reported in the literature.…”

Performance of N3 Sensitized Titania Solar Cell under Artificial Light Ambience

“…Moreover, they often use 12 toxic and scarce materials. The third generation solar cells such as dye sensitized solar cells (DSSCs) have attracted considerable interest during the past two decades due to their potential as a low cost and 13 easily processable alternative to traditional solid state solar cells. These solar cells can be used for outdoor and indoor light harvesting and conversion of light into electricity.…”

Synthesis and Characterization of Diethylphosphonate and Carboxylate-appended Iridium Complexes for the Application on Dye-Sensitized Solar Cells

“…Sensitizers presenting metal‐to‐ligand charge transfer states are very sensitive to the spatial separation with the electrode surface. Unfortunately, an increase of this separation would decrease the back recombination but at the same time may be detrimental to the injection efficiency . In contrast, LLCT may increase separation distance bringing more stability to the π‐π* states, and also to the MLCT transition.…”

“…Unfortunately, an increase of this separation would decrease the back recombination but at the same time may be detrimental to the injection efficiency. [32][33][34] In contrast, LLCT may increase separation distance bringing more stability to the p-p* states, and also to the MLCT transition. In addition, according to the literature, cyclometalated iridium(III) complexes present less accessible MC states compared to ruthenium-bipyridine based.…”