Melas-Kyriazi, JohnDing, I.-KangMarchioro, AriannaPunzi, AngelaHardin, Brian E.Burkhard, George F.Tétreault, NicolasGrätzel, MichaelMoser, Jacques-E.Mcgehee, Michael D.2011-05-162011-05-162011-05-16201110.1002/aenm.201100046https://infoscience.epfl.ch/handle/20.500.14299/67388WOS:000291728400016A detailed investigation of the effect of hole transport material (HTM) pore filling on the photovoltaic performance of solid-state dye-sensitized solar cells (ss-DSCs) and the specific mechanisms involved is reported. It is demonstrated that the efficiency and photovoltaic characteristics of ss-DSCs improve with the pore filling fraction (PFF) of the HTM, 2,2’,7,7’-tetrakis-( N, N-di-p-methoxyphenylamine)9,9’-spirobifluorene(spiro-OMeTAD). The mechanisms through which the improvement of photovoltaic characteristics takes place were studied with transient absorption spectroscopy and transient photovoltage/photocurrent measurements. It is shown that as the spiro- OMeTAD PFF is increased from 26% to 65%, there is a higher hole injection efficiency from dye cations to spiro-OMeTAD because more dye molecules are covered with spiro-OMeTAD, an order-of-magnitude slower recombination rate because holes can diffuse further away from the dye/HTM interface, and a 50% higher ambipolar diffusion coefficient due to an improved percolation network. Device simulations predict that if 100% PFF could be achieved for thicker devices, the efficiency of ss-DSCs using a conventional ruthenium dye would increase by 25% beyond its current value.Photoinduced Absorption-SpectroscopyEnergy Relay DyesCharge-TransferEfficiency MeasurementsRecombination KineticsRuthenium SensitizersDiffusion LengthSpiro-MeotadTio2Electrontext::journal::journal article::research article