Based on the previous research work in our laboratory, we have designed and synthesized a small-molecule,hole transport material(HTM) POZ6-2 using phenoxazine(POZ) as central unit and dicyanovinyl units as electron-withdrawing terminal groups. Through the introduction of a 2-ethyl-hexyl bulky chain into the POZ core unit, POZ6-2 exhibits good solubility in organic solvents. In addition, POZ6-2 possesses appropriate energy levels in combination with a high hole mobility and conductivity in its pristine form. Therefore, it can readily be used as a dopant-free HTM in perovskite solar cells(PSCs) and a conversion efficiency of 10.3% was obtained. The conductivity of the POZ6-2 layer can be markedly enhanced via doping in combination with typical additives, such as 4-tert-butylpyridine(TBP) and lithium bis(trifluoromethanesulfonyl) imide(Li TFSI).Correspondingly, the efficiency of the PSCs was further improved to 12.3% using doping strategies. Under the same conditions, reference devices based on the well-known HTM Spiro-OMe TAD show an efficiency of 12.8%.
Ming ChengCheng ChenBo XuYong HuaFuguo ZhangLars KlooLicheng Sun
Understanding the seven coordination and O-O coupling pathway of the distinguished Ru-bda catalysts is essential for the development of next generation efficient water-oxidation catalysts based on earthabundant metals.This work reports the synthesis,characterization and catalytic properties of a monomeric ruthenium catalyst Ru-bnda(H2 bnda=2,2’-bi(nicotinic acid)-6,6’-dicarboxylic acid)featuring steric hindrance and enhanced hydrophilicity on the backbone.Combining experimental evidence with systematic density functional theory calculations on the Ru-bnda and related catalysts Ru-bda(H_(2)bda=2,2’-bipyridine-6,6’-dicarboxylic acid),Ru-pda(H_(2)pda=1,10-phenanthroline-2,9-dicarboxylic acid),and Ru-biqa(H_(2)biqa=(1,1’-biisoquinoline)-3,3’-dicarboxylic acid),we emphasized that seven coordination clearly determines presence of Ru^(Ⅴ)=O with high spin density on the ORu^(Ⅴ)=O atom,i.e.oxo with radical properties,which is one of the necessary conditions for reacting through the O-O coupling pathway.However,an additional factor to make the condition sufficient is the favorable intermolecular faceto-face interaction for the generation of the pre-reactive[Ru^(Ⅴ)=O…O=Ru^(Ⅴ)],which may be significantly influenced by the secondary coordination environments.This work provides a new understanding of the structure-activity relationship of water-oxidation catalysts and their potential to adopt I2M pathway for O-O bond formation.
Dye-sensitized photoelectrochemical cell(DS-PEC) is an especially attractive method to generate hydrogen via visible light driven water splitting. Electrolyte, an essential component of DS-PEC, plays a great role in determining the photoactivities of devices for water splitting. When using phosphate buffer(pH = 6.4)as electrolyte, the DS-PEC displayed much higher photoactivity than using 0.1 M Na_2SO_4(pH = 6.4) as electrolyte. The insight is phosphate anion gathers together to form a negative electrostatic field on TiO_2 surface, which increases the resistance in the TiO_2/catalyst and electrolyte interface and validly reduces the charge recombination from TiO_2 to the oxidized catalyst.
Adsorption state of catalyst on photoanode is an important factor on influencing the performance of dye-sensitized photoelectrochemical cells(DS-PECs) for water splitting. Photoanode TiO_2(1 + 2) was assembled with Ru(bpy)3phosphoric acid derivative(complex 1) as photosensitizer and complex 2 as water oxidation catalyst to compare with photoanode TiO_2(1 + 3). The photocurrent density of photoanode TiO 2(1 + 3) with catalyst 3 synthesized with only one end fixing on the surface of TiO_2 is about four-fold of the photoanode assembled with catalyst 2 fixing with two claws on the surface of TiO 2. The phenomenon should be caused by the littery arrangement and shorter distance of catalyst 2 from the active center of catalyst to TiO_2 on the surface of semiconductor which led to lowly efficient electron transfer.
＜正＞Graphitic carbon nitride （g-C3N4）, a metal-free semiconductor, is a promising new class of photocatalysts f...
Jingfeng Dong1,Mei Wang1,*,Xueqiang Li1,Lin Chen1,Yu He1,Licheng Sun1,2 1State Key Laboratory of Fine Chemicals,DUT-KTH Joint Education and Research Center on Molecular Devices,Dalian University of Technology(DUT),Dalian,116012,China 2Department of Chemistry,Royal Institute of Technology(KTH),Stockholm,10044 Sweden
