Quantum Dot−Dye Bilayer-Sensitized Solar Cells: Breaking the Limits Imposed by the Low Absorbance of Dye Monolayers

Abstract

Here, we present a new DSSC design, consisting of sequential QDs and dye sensitization layers, that opens the path toward high optical density DSSCs that cover a significant part of the solar spectrum. The new configuration is enabled by the application of an amorphous TiO2 layer between the two sensitizers, allowing both electron injection from the outer absorber and fast hole extraction from the inner sensitizing layer. Utilizing two sensitizing layers, we obtain a 250% increase in cell efficiency compared to a QD monolayer cell.

Super Sensitization: Grand Charge (Hole/Electron) Separation in ATC Dye Sensitized CdSe, CdSe/ZnS Type‐I, and CdSe/CdTe Type‐II Core–Shell Quantum Dots

“…The instrument response function (IRF) for 400 nm excitation was obtained by fitting the rise time of the bleach of sodium salt of mesotetrakis (4-sulfonatophenyl) porphyrin (TPPS) at 710 nm and was found to be 120 fs. The concentration of CdTe samples was 10-5 m as calculated from the extinction coefficient from Rogach et al 20 at the exciton peak position. The hNi = js value was maintained at 0.1 excitons per particle to avoid multi particle relaxation processes like the Auger process (a detailed description of the femtosecond transient absorption spectrometer is reported in the Supporting Information).…”

“…[14][15][16][17][18] In addition to that, it has been realized that limited absorption of solar radiation of QDs and a slow hole-transfer rate are the main reasons for overall low efficiency of QDSC. These problems can be tackled by introducing super sensitizers in QDSC, [3,4,[19][20][21] in which quantum dots and molecular adsorbates can exchange charge carriers on photoexcitation. In super sensitization, in addition to photosensitizing the quantum dot material, the molecular adsorbate can also act as hole transporting material for photosensitized quantum dots, and as a result grand charge separation takes place in QD-molecular composite materials.…”

Ultrafast characterization of the electron injection from CdSe quantum dots and dye N719 co-sensitizers into TiO2 using sulfide based ionic liquid for enhanced long term stability

“…8,9 In addition, semiconductor QDs are excellent building blocks for the design of light supracollecting structures by the synergetic combination of different types of QDs, 10,11 or QDs and dyes. [12][13][14][15][16][17][18][19][20] Different QDs and dye hybrid systems have been explored with the aim to exploit their interacting proprieties. In this heterostructures, performance can arise from the fast scavenging of photogenerated holes in quantum dots by a molecular dye.…”

“…15,19 Simultaneously, the combined use of QD and dye enhances the light harvesting wavelength range due to the combined absorption of the two assembled sensitizers. 12,17,18 Although hybrid sensitized systems appear promising, only few examples have been…”

Electrospun TiO2 microspheres as a scattering layer for CdS quantum dot-sensitized solar cells

“…Sensitized solar cells are considered as a promising candidate for the development of next generation solar cells because they can be fabricated by simple and low-cost techniques [1][2][3][4][5][6][7]. Recently, plenty of research has been carried out to improve the performance of quantum dot-sensitized solar cells (QDSSCs) by various methods [8][9][10][11][12][13][14][15][16][17][18][19].…”