We report two new triarylamine-cyanoacrylic acid based push–pull dyes, X76 and X77, featuring the π-conjugated linkers of dihexyl- and dihexyloxybenzene-substituted dithieno[2,3-d:2′,3′-d′]thieno[3,2-b:3′,2′-b′]dipyrrole (DTDP), respectively.

No abstract

Indoline photosensitizers exhibit impressive short-circuit photocurrent but generally low molar extinction coefficient and rapid charge recombination, which limits their application in thin-film dye-sensitizerd solar cells (DSCs). Here, we incorporate a new dithieno[3,2-b:2',3'-d]pyrrole (DTP) segment (i.e., dihexyloxy-triphenylamine (DHO-TPA) substituted DTP) as the conjugated π-linker to construct a series of high molar absorption coefficient indoline dyes (XW69, XW70, and XW71) for DSCs employing a cobalt(II/III) redox electrolyte. Interestingly, this DTP linker is demonstrated as an efficient building block, not only slowing down the kinetics of charge recombination of titania electrons with tris(1,10-phenanthroline)cobalt(III) ions but also making a great contribution to the light absorption properties in comparison with the dihexylaniline substituted DTP. With respect to the dihexyloxy-triphenylamine dye (XW68), these new indoline dyes exhibit stronger light-harvesting and thus better power conversion efficiency of DSCs made from thin titania films. Benefitting from the bulky rigidity of the donor and π-conjugation unit, the XW70 dye displays a promising conversion efficiency as high as 8.78%, with a short-circuit current density (J(SC)) of 13.3 mA cm(-2), open-circuit voltage (V(OC)) of 943 mV, and fill factor (FF) of 0.70 under AM 1.5 illumination (100 mW cm(-2)). Furthermore, the effect of light irradiation on these dyes adsorbed on nanocrystalline TiO2 films was investigated, proving the photostability of these indoline chromophores. Our work has valued the feasibility of judicious design of indoline chromophores to obtain organic photosensitizers for high-efficiency iodine-free DSCs made from thin titania films.

Two P-type organic molecules containing indolocarbazole and methoxy (or methylthio) substituted triphenylamine are designed and synthesized as interface layers to passivate surface defects and meanwhile protect perovskite films from water.

A series of D-π-A organic dyes, X72-75, containing novel triarylamine electron donors have been synthesized for dye-sensitized solar cells (DSCs). The superiority of the asymmetric design of the triphenylamine electron donor over the symmetrical triphenylamine when applied in organic dyes for cobalt cells has been observed. Using X72 with the cobalt(II/III) redox shuttle resulted in an overall power conversion efficiency (PCE) of 9.18%, outperforming the state-of-the-art dye C218 under the same conditions.

No abstract

In order to overcome the problem of poor quality of perovskite films obtained from alcohol alike green antisolvents, we herein introduce an additive, tryptaminium iodide (TPAI), into an isopropanol (IPA) green antisolvent to fabricate high-quality perovskite films toward efficient and stable perovskite solar cells (PSCs). The interactions between perovskite (methylammonium lead iodide, MAPbI 3 ) and TPAI are systematically and deeply investigated by means of X-ray photoelectron spectroscopy and proton nuclear magnetic resonance. It is found that there exist coordination and hydrogen bonds between TPAI and MAPbI 3 , which causes preferred orientation growth of perovskite crystals, notable passivation of traps, enhanced carrier extraction, and suppressed charge recombination. Consequently, the green antisolvent additive engineering enhances the power conversion efficiency (PCE) from 17.27 to 20.40%. Furthermore, the PSC prepared through the green antisolvent additive engineering maintains 81% of the initial PCE when stored in the ambient condition for 1000 h, in contrast to 56% for the PSC based on the IPA antisolvent without an additive.

As all-inorganic perovskite (CsPbI3–x Br x ) is prone to phase transition from the α phase (black phase) to the δ phase (yellow phase) in a humid environment or under heating, improving the phase stability of all-inorganic perovskite of the black phase is one of the urgent problems to solve. Herein, 1,2-dimethyl-3-acetylimidazolium iodide (DMAII) is spin-coated onto the surface of CsPbI3–x Br x perovskite for use in p–i–n perovskite solar cells (PSCs). We find that the DMAII coating has two effects on the CsPbI3–x Br x perovskite film: surface passivation and phase stabilization of perovskite. Traps in the CsPbI3–x Br x perovskite film can be reduced significantly by DMAII passivation, resulting in enhanced hole extraction and suppressed charge recombination. Consequently, the power conversion efficiency (PCE) is improved from 10.81 to 13.14%. Moreover, the DMAII coating can significantly inhibit the phase transition from the α phase to the δ phase in a humid environment or under heating, as characterized by the X-ray diffraction pattern, UV–vis absorption spectrum, and film color. After exposing the CsPbI3–x Br x perovskite films to a humid atmosphere (relative humidity = 40–60%) for 6 h, the PCE decreases dramatically to only 0.12% of the initial PCE for the PSC without the DMAII coating, while the PCE maintains 80% of the initial PCE for the PSC with the DMAII coating. In addition, when the PSC devices are heated at 120 °C for 4 h, the control PSC shows a 96% decrease in PCE, while the PCE decay is only 9% for the DMAII-coated PSC. These findings indicate that carboxyl-substituted imidazolium iodide is a kind of promising material to not only passivate traps but also stabilize the black phase of all-inorganic perovskite.