Energy and Electron Transfer Cascade in Self-Assembled Bilayer Dye-Sensitized Solar Cells

Abstract

Current high efficiency dye-sensitized solar cells (DSSCs) rely on the incorporation of multiple chromophores, via either codeposition or preformed assemblies, as a means of increasing broad band light absorption. These strategies have some inherent limitations including decreased total light absorption by each of the dyes, low surface loadings, and complex synthetic procedures. In this report, we introduce an alternative strategy, self-assembled bilayers, as a simple, stepwise method of incorporating two complementary chromophores into a DSSC. The bilayer devices exhibit a 10% increase in J, V, and η over the monolayer devices due to increased incident photon-to-electron conversion efficiency across the entire visible spectrum and slowed recombination losses at the interface. Directional energy and electron transfer toward the metal oxide surface are key steps in the bilayer photon-to-current generation process. These results are important as they open the door to a new architecture for harnessing broadband light in dye-sensitized devices.

In-Situ Electropolymerized Polyamines as Dopant-Free Hole-Transporting Materials for Efficient and Stable Inverted Perovskite Solar Cells

“…The lower-energy absorption spectra of these films are slightly expanded with that of the monomer 1 in CH 2 Cl 2 (Figure b), possibly caused by the molecular aggregation in the film state. The coverage Γ of these films was estimated by Γ = A 350nm /(ε 350nm × 1000), where A 350nm and ε 350nm refer to the absorbance of the film at 350 nm and the molar extinction coefficient of the monomer 1 at 350 nm (ε 350nm = 0.58 × 10 –5 M –1 cm –1 ), respectively, assuming that the monomer and polymer have similar molar extinction coefficients at this wavelength . In this sense, films poly- 1 (A) to poly- 1 (D) have a Γ of 2.6 × 10 –9 , 3.1 × 10 –9 , 4.6 × 10 –9 , and 5.7 × 10 –9 mol/cm 2 , respectively.…”

Harnessing near-infrared lightviaS0to T1sensitizer excitation in a molecular photon upconversion solar cell

“…4), we saw no evidence of Os to A + electron transfer occurring in the TiO 2 - A -Zn- Os film. While interlayer electron transfer has been observed, 50 the increased distance and geometric constraint imparted by the metal ion linkage can also hinder electron transfer. 48 Consequently, the post injection cation resides on A and is likely the site of regeneration where access by the mediator is still possible due to the lower surface coverage of Os relative to A (∼7 : 1).…”

The effect of co-sensitization methods between N719 and boron dipyrromethene triads on dye-sensitized solar cell performance

“…Although we do not fully understand the reason for greater J sc values of stepwise co-sensitization, we assume that this may be due to cascade electron transfer from BD to N719 to titania since BD has higher LUMO energy level (À3.7 eV) than that of N719 (À3.9 eV). 47,48 Fig. 7 J-V characteristics of DSCs containing BD, N719 and cosensitized N719 + BD solar cells.…”