Three new donor−acceptor−donor type (D−A−D) hole-transporting materials (HTMs), YC-1−YC-3, based on the 4-dicyanomethylene-4Hcyclopenta [2,1-b;3,4-b′]dithiophene (DiCN-CPDT) core structure endowed with two arylamino-based units as peripheral groups were designed, synthesized, and applied in perovskite solar cells (PSCs). Hole mobility, steady-state photoluminescence, thin-film surface morphology on top of the perovskite layer, and photovoltaic performance for the YC series were systematically investigated and compared with those of Spiro-OMeTAD. It was found that YC-1 exhibited more efficient hole transport and extraction characteristics at the perovskite/HTM interface. Meanwhile, the film of YC-1 showed a homogeneous and dense capping layer coverage on the perovskite layer without any pinholes, leading to the improvement of the fill factor and open circuit voltage. The PSC device based on YC-1 as a HTM exhibited a high power conversion efficiency (PCE) of 18.03%, which is comparable to that of the device based on the benchmark Spiro-OMeTAD (18.14%), and also a better long-term stability with 85% of the initial efficiency retained in excess of 500 h under the condition of 30% relative humidity, presumably due to the hydrophobic nature of the material. This work demonstrates that the dicyanomethylene-CPDT-based derivatives are promising HTMs for efficient and stable PSCs.

A series of small‐molecule‐based hole‐transporting materials (HTMs) featuring a 4H‐cyclopenta[2,1‐b : 3,4‐b′]dithiophene as the central core with triphenylamine‐ and carbazole‐based side groups was synthesized and evaluated for perovskite solar cells. The correlations of the chemical structure of the HTMs on the photovoltaic performance were explored through different combinations of the central π‐bridge moieties. The optical and electrochemical properties, energy levels, and hole mobility were systematically investigated, revealing the significant influence of the central core planarity and packing structure on their photovoltaic performance. The optimized device based on CT1 exhibited a PCE (power conversion efficiency) of 17.71 % with a device architecture of FTO/TiO2 compact layer/TiO2 mesoporous/CH3NH3PbI3/HTM/MoO3/Ag, which was found to be on par with that of a cell fabricated based on state‐of‐the‐art spiro‐OMeTAD (16.97 %) as HTM. Moreover, stability assessment showed an improved stability for CPDT‐based HTMs in comparison with spiro‐OMeTAD over 1300 h.

A new class of hole-transport materials (HTMs) based on the bimesitylene core designed for mesoporous perovskite solar cells is introduced. Devices fabricated using two of these derivatives yield higher open-circuit voltage values than the commonly used spiro-OMeTAD. Power conversion efficiency (PCE) values of up to 12.11% are obtained in perovskite-based devices using these new HTMs. The stability of the device made using the highest performing HTM (P1) is improved compared with spiro-OMeTAD as evidenced through long-term stability tests over 1000 h.

A stilbene-based compound (1) has been prepared and was highly selective for the detection of cyanide anion in aqueous media even in the presence of other anions, such as F(-), Cl(-), Br(-), I(-), ClO(4)(-), H(2)PO(4)(-), HSO(4)(-), NO(3)(-), and CH(3)CO(2)(-). A noticeable change in the color of the solution, along with a prominent fluorescence enhancement, was observed upon the addition of cyanide. The color change was observed upon the nucleophilic addition of the cyanide anion to the electron-deficient cyanoacrylate group of 1. The spectral changes induced by the reaction were analyzed by comparison with two model compounds, such as compound 2 with dimethyl substituents and compound 3 without a cyanoacrylate group. An intramolecular charge-transfer (ICT) mechanism played a key role in the sensing properties, and the mechanism was supported by DFT/TDDFT calculations.

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A series of new pyridomethene-BF2/phenothiazine-hybrid metal-free organic sensitizers K1-K8 containing different πspacers were synthesized and applied in dye-sensitized solar cells (DSSC). The introduction of the pyridomethene-BF2 complex unit to the phenothiazine chromophore displayed a high molar extinction coefficient in favor of light-harvesting. Quantum chemical calculations were performed by using the density functional theory (DFT) at the B3LYP/6-31G (d,p) level to investigate the structural properties and electron density distributions of these dyes. The effect of dyes K1-K8 on the performance of DSSC was investigated systematically with comparisons to the plane phenothiazine dyes R1 and R2. Upon co-adsorption with deoxycholic acid, the dye K3 with a thiophene unit between the phenothiazine and pyridomethene-BF2 units exhibited the best photovoltaic performance. The short-circuit current density (Jsc) was 15.43 mA cm -2 with an open-circuit voltage (Voc) 0.69 V and a fill factor (FF) 0.62, that corresponded to a power-conversion efficiency (η) 6.58% under AM 1.5G irradiation (100 mW．cm -2 ) condition. The n-hexyl chain attached to the thiophene in K4-K5 exhibitted an effect of improving the Voc value. The presence of the phenyl pyridomethene-BF2 moiety at the N(10) atom of phenothiazine in K6-K8 showed a good effect of reducing π-π aggregation. These results revealed the advantage of incorporating a pyridomethene-BF2 group in the dyes for high performance DSSC cells.

A new cyclopentadithiophene (CPDT)-based organic small molecule serves as an efficient dopant-free hole transporting material (HTM) for perovskite solar cells (PSCs). Upon incorporation of two carbazole groups, the resulting CPDT-based...