Recent developments in sensitized mesoporous heterojunction solar cells

Abstract

The performance of solid-state dye-sensitized solar cells based on spiro-MeOTAD (2,2'7,7'-tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9'-spirobifluorene) was considerably improved by decreasing charge recombination across the interface of the heterojunction. This was achieved by blending the hole conductor matrix with a combination of 4-tert-butylpyridine (tBP) and Li[CF3SO2]2N. Open circuit voltages (Uoc) over 900mV and short circuit currents (Isc) up to 5.1 mA were obtained, yielding an overall efficiency of 2.56 % at AM1.5 illumination. Further improvement of the device performance was observed when conducting stripes of silver were deposited onto the devices as charge collector. The beneficial effect however could be assigned to the contamination of the dye-sensitized TiO2 film with silver during the dyeing process.

p-type oxide semiconductors as hole collectors in dye-sensitized solid-state solar cells

“…In such solar cells the main problem is that the liquid electrolyte limits device stability owing to the evaporation of the liquid electrolyte as the perfect sealing of solar cells is not possible. Recently liquid electrolytes have been replaced by molten salts, inorganic p-type semiconductors, organic hole transport materials, ionic liquid electrolytes and polymer electrolytes [4][5][6][7][8][9][10]. The solid state dye sensitized solar cell (SS-DSSC) often met problems of short-circuit and mass transport limitations of the ions resulting in low conversion efficiencies compared with the liquid version.…”

Molten and Solid Trialkylsulfonium Iodides and Their Polyiodides as Electrolytes in Dye-Sensitized Nanocrystalline Solar Cells

“…Quasi-solid-state electrolytes of HMImI and iodine with addition of low-molecular-weight gelators have been investigated by Kubo and co-workers. , Solid-state amorphous organic hole-transport materials have been successfully tested as mediators by Grätzel and co-workers . Modifications of these compounds have provided improved results in solar cell measurements. − …”

“…15 Modifications of these compounds have provided improved results in solar cell measurements. [16][17][18] Trialkylsulfonium polyiodides have been found to exhibit good electrical conductivity, 10 -3 to 10 -4 S/cm, which increases with larger contents of iodine. 19 This is explained by a mechanism of electrical conduction in polyiodide chains via a Grotthus mechanism, a relay mechanism, in which a net transport of charge is achieved without any net transport of mass.…”