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A pair of isomeric hexafluorinated oligomers (Th6FSe and Se6FTh), which are with the same aromatic compositions (difluorobenzothiadiazoles central core, IDT units, and donor end-capped groups), but differ in the π-bridge position (selenophene and thiophene), were designed and successfully synthesized. The potential of the resulted oligomers as donor materials for BHJ-OSCs was systematically investigated through optical absorption, AFM, TEM, GIXD, charge mobility measurement, and photovoltaic device fabrication. It was found that the π-bridge sequences in the resulted oligomers play a subtle but key role in device performances. Moreover, as a result of increase of crystalline content and desired phase separation after rapid SVA or combined TA and SVA treatment, the device performance of the resultant devices undergo significant enhancement. Notably, the Se6FTh devices showed a best PCE of ca. 9.3% with SVA+TA treatment, which is the highest PCE of BHJ-OSCs based on donor end-capped oligomers. These primary...

This work investigates the anisotropic PEC performances of ZnO single-crystalline (SC) photoanodes and the effect of internal electrostatic fields on the separation of photogenerated charge carriers during PEC water splitting. It was found that the internal electrostatic field can greatly influence the bulk charge separation efficiencies during PEC water splitting depending on its orientations, which can only be promoted as the internal electrostatic field in accordance with the direction of the holes’ transportation. Due to the surface stabilization of ZnO polar surfaces, the internal electrostatic field would be gradually decreased to zero near the surface of ZnO SC photoanodes. Therefore, the interfacial charge separation would be mainly determined by the interfacial electric fields in the space charge region formed by the equilibration of the Fermi levels between ZnO and the electrolyte solution. However, the differences on the bulk charge separation efficiencies of ZnO SC photoanodes are much larger ...

A family of narrow band gap extended π-conjugated D2-A2-D1-A1-D1-A2-D2 type small molecules based on diketopyrrolopyrrole derivatives as the stronger acceptor core (A1) coupled with indacenodithiophene (IDT; D1) and difluorobenzothiadiazole (A2) are synthesized, and their properties as donor materials in solution-processed small-molecule organic solar cells are investigated. The impacts of replacing the thiophene ring by a more electron-deficient thiazole ring and inserting thiophene spacer between electron-donating (D1) and electron-accepting (A1 and A2) aromatic moieties on bulk properties, such as the photophysical properties, the HOMO/LUMO energy level, charge carrier mobilities, and the morphologies of blend films, as well as optimization on device performance via solvent vapor annealing are investigated. NDPPFBT shows outstanding efficiencies up to 7.00% after THF vapor annealing for 60 s because of a very high fill factor (FF) of 0.73 and high Voc of 0.89 V. The reported efficiency is among one of ...

CaAl2O4:Eu is a persistent luminescence (PL) material in the blue light region with potentially wide commercial applications. With the doping of Nd, the decay time can be elongated to more than 19 h. These excellent properties are believed to be in close relation with the electronic structures of the dopants, the defects, and the host material. In this work, we attempt to achieve a better understanding of the PL mechanism of CaAl2O4:Eu based on first-principles calculations. The electronic structures of the host CaAl2O4, the luminescent center Eu, the O and Ca vacancies, and the dopant Nd are systematically studied. According to the calculations, the 4f and 5d levels of Eu are located within the band gap and slightly above the conduction band minimum (CBM), respectively. The electrons on the 4f levels can be excited into the 5d levels via ultraviolet radiation. The excited electrons on the 5d levels can move to the conduction bands and become free electron carriers. The electron carriers can be trapped fo...

The effect of different alkali metal ions (Li+, Na+, K+) incorporated into aluminas on the gate dielectric behavior of solution processed oxide field-effect transistors (FETs) was studied. High field-effect mobility (ca. 20 cm2·V–1·s–1), high saturation drain current (about 1 mA), and low subthreshold swing (ca. 200 mV/decade) were achieved in low-voltage (2 V), spin-coated zinc-tin-oxide (ZTO) FETs with potassium alumina (PA) and lithium alumina (LA) dielectrics, as we had previously demonstrated with sodium alumina (SA). To investigate the effect of alkali metal ion on the detailed alumina capacitance and AC conductivity response, the frequency, temperature, and thickness dependences of alumina capacitance were determined. Ion-incorporated alumina metal–insulator–metal (MIM) capacitors showed a possible electric double layer capacitor (EDLC) behavior, in contrast to what was observed for alumina itself. The frequency dependence of observed capacitance varied with the included ion. These dependences were...

Ru/RuO2 core−shell nanoparticles were synthesized by electrochemical method in water without the addition of stabilizers. The zeta potential of the fresh nanoparticles was 30.8 mV in pure water at 25 °C, confirming that the repulsion between the particles is strong enough to stabilize them in aqueous solution. When the Ru/RuO2 nanoparticles were loaded on metal oxide supports (CeO2, TiO2 and Al2O3), the structure of Ru core and RuO2 shell remained unchanged on CeO2 support, whereas Ru core was preferred to be oxidized to RuO2 on TiO2 and Al2O3. The catalytic oxidations of ethanol were chosen to compare the catalytic properties of the Ru/RuO2 nanoparticles supported catalysts (our method) with that of Ru catalysts prepared by traditional wet impregnation method. All catalysts prepared by our method showed higher catalytic activities for the catalytic oxidations of ethanol than the Ru catalysts prepared by wet impregnation.