A simple hydrothermal method with titanium tetraisopropoxide (TTIP) as a precursor and triethanolamine (TEOA) as a chelating agent enabled growth in the presence of a base (diethylamine, DEA) of anatase titania nanocrystals (HD1-HD5) of controlled size. DEA played a key role to expedite this growth, for which a biphasic crystal growth mechanism is proposed. The produced single crystals of titania show octahedron-like morphology with sizes in a broad range of 30-400 nm; a typical, extra large, octahedral single crystal (HD5) of length 410 nm and width 260 nm was obtained after repeating a sequential hydrothermal treatment using HD3 and then HD4 as a seed crystal. The nanocrystals of size ~30 nm (HD1) and ~300 nm (HD5) served as active layer and scattering layer, respectively, to fabricate N719-sensitized solar cells. These HD devices showed greater V(OC) than devices of conventional nanoparticle (NP) type; the overall device performance of HD attained an efficiency of 10.2% power conversion at a total film thickness of 28 μm, which is superior to that of a NP-based reference device (η = 9.6%) optimized at a total film thickness of 18-20 μm. According to results obtained from transient photoelectric and charge extraction measurements, this superior performance of HD devices relative to their NP counterparts is due to the more rapid electron transport and greater TiO(2) potential.

The excitonic relaxation dynamics of perovskite adsorbed on mesoporous thin films of Al2O3 and NiO upon excitation at 450 nm were investigated with femtosecond optical gating of photoluminescence (PL) via up-conversion. The temporal profiles of emission observed in spectral region 670-810 nm were described satisfactorily with a composite consecutive kinetic model and three transient components representing one hot and two cold excitonic relaxations. All observed relaxation dynamics depend on the emission wavelength, showing a systematic time-amplitude correlation for all three components. When the NiO film was employed, we observed an extent of relaxation proceeding through the non-emissive surface state larger than through the direct electronic relaxation channel, which quenches the PL intensity more effectively than on the Al2O3 film. We conclude that perovskite is an effective hole carrier in a p-type electrode for NiO-based perovskite solar cells showing great performance.

We designed a dimeric porphyrin dye based on an efficient push–pull zinc porphyrin with extended π-conjugation so that the light-harvesting ability exhibits a panchromatic feature covering a broad spectral region from 400 nm to 900 nm.

The excitonic relaxation dynamics of perovskite adsorbed on mesoporous thin films of Al 2 O 3 and NiO upon excitation at 450 nm were investigated with femtosecond optical gating of photoluminescence (PL) via up-conversion. The temporal profiles of emission observed in spectral region 670-810 nm were described satisfactorily with a composite consecutive kinetic model and three transient components representing one hot and two cold excitonic relaxations. All observed relaxation dynamics depend on the emission wavelength, showing a systematic time-amplitude correlation for all three components. When the NiO film was employed, we observed an extent of relaxation proceeding through the nonemissive surface state larger than through the direct electronic relaxation channel, which quenches the PL intensity more effectively than on the Al 2 O 3 film. We conclude that perovskite is an effective hole carrier in a p-type electrode for NiO-based perovskite solar cells showing great performance.

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