A New Type of Electrolyte with a Light‐Trapping Scheme for High‐Efficiency Quasi‐Solid‐State Dye‐Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) are attracting both academic and industrial interest owing to their high-effi ciency and potential low-cost. [ 1 ] The electrolyte, containing the I − /I 3 − redox couple, is the one of the most-important components of a DSSC, and directly infl uences their performance and stability. [ 2,3 ] Generally, the role of the electrolyte in a DSSC is to fi nish the charge cycle, including the transport of the I − /I 3 − redox couple, [ 4 ] the regeneration of oxidized dye at the dyed TiO 2 /electrolyte interface and the reduction of I 3 − at the counter electrode. [ 5 ] However, I 3 − in the electrolyte will absorb visible light, [ 6 ] which results in energy loss. Furthermore, due to the inhomogeneous dye distribution, [ 7 ] a certain part of the incident light transmits through the photoanode, which decreases the light-harvesting effi ciency. As we know, although relatively large particles have already been used in DSSCs to help increase the light-harvesting effi ciency, still part of the incident light will transmit through the photoanode. Moreover. an excess of large particles will not only lower the light-harvesting effi ciency over the whole range of visible wavelengths owing to enhanced light refl ection at the conducting glass/TiO 2 interface, but also decrease the electron-transfer yield. [ 8 ] As reported previously, [ 9 ] light trapping has become a standard technique to increase the light absorption of incident light in the active layers of hydrogenated amorphous-siliconbased solar cells, based on the use of textured substrates and highly refl ective back contacts. This triggered our interest in exploring a new type of electrolyte with a light-trapping scheme to enhance the light-harvesting effi ciency of DSSCs. Liquid crystals (LCs), as the fourth state of matter, combining properties of liquids and solids, [ 10 ] are usually used as the medium for organic catalytic synthesis, [ 11 ] functional nanostructured materials, [ 12 ] and especially in the fi eld of polymer-dispersed liquidcrystal (PDLC) displays, due to the light-scattering properties of the LC. [ 13 ] Thus, we tried to introduce an LC to the liquid electrolyte of a DSSC. Furthermore, when the LC was added to the liquid electrolyte, a quasi-solid-state electrolyte was formed, which could help to resolve the sealing diffi culty in the DSSCs.