Organic cathode materials for rechargeable metal-ion batteries have attracted much attention, while their applications are still limited by the unsatisfactory voltage platform owing to the low conductivity and high solubility of organic materials in the electrolyte. Rational molecular design is a promising way to solve the aforementioned problems. Dihydrophenazine (Pz) and its derivatives with high theoretical specific capacity and suitable oxidation–reduction potential are promising as ideal p-type cathode materials. Herein, the electron donating 5,10-dihydrophenazine is combined with the electron-withdrawing pyridine derivatives, and two donor–acceptor type polymers (BPyPz and TPyPz) are thus developed and successfully applied as p-type cathodes. The active site on Pz is affected by the position of the pyridine group, which significantly affects the redox potential and electrochemical properties of the materials. The structure–property relationship is investigated through density functional theory calculations and various electrochemical tests. BPyPz with pyridine connected to dihydrophenazine at the 2,5- position provides high reversible specific capacities of 205 mA h g⁻¹ in a half-cell and 162 mA h g⁻¹ in a full-cell, respectively. Notably, the average voltage of the full-cell is as high as 3.0 V, which is among one of the highest voltage platforms for organic cathodes in full-cells. Therefore, this work demonstrates the potential of sodium-based dual-ion full cells, and may provide guidance for the future design of high-voltage organic cathode materials.

2,5-Bis-( p -benzoquinonyl) furan was developed as the cathode material for SIBs, furan as the bridge group endows good planarity of the whole molecule, and it also works as an additional storage site for PF ₆ ⁻ .

Rational design of hole transport materials (HTMs) can significantly enhance the performance of perovskite solar cells (PSCs). In this work, in order to provide a strategy of molecular design, three HTMs (JY4–JY6) are designed through modulating the intermolecular interactions within carbazole-diphenylamine-based HTMs for enhancing the efficiency of PSCs. On the basis of the DFT, TD-DFT, Marcus theory, and MD simulations, though the designed HTMs exhibit similar electron structures, optical properties and solubility, trifluoromethoxy isomerization in the designed HTMs can yield different intermolecular interactions and surface adsorption on perovskite films. Specifically, the molecule of JY6 demonstrates an inter-molecular co-directional alignment, which can offer an additional C–H/π stacking pathway for promoting a strong electronic-coupling between the adjacent molecules. Related experiments further confirmed heightened hole mobility, smoother film morphology, enhanced hole extraction and reduced charge recombination at the perovskite/JY6 interface. Therefore, PSC devices based on JY6 achieve a champion PCE of 22.06% compared to the devices based on JY4 (PCE of 18.84%) and JY5 (PCE of 20.94%) under equivalent conditions. Through a combination of theoretical calculations and experimental exploration, we substantiate the feasibility of obtaining potential HTMs via trifluoromethoxy isomerization to modulate the intermolecular interactions for enhancing the efficiency of PSCs.

We present an effective strategy to modulate the electron-deficiency of the π-bridged units in bis(4-methoxyphenyl)amine-based hole-transporting materials (HTMs) for improving hole mobility and the performances of perovskite solar cells (PSC) devices. In order to confirm this strategy, on the basis of the reported bis(4-methoxyphenyl)amine-based pDPA-DBTP, we adjusted the electron-deficiency of π-bridge units in pDPA-DBTP, and designed a series of new HTMs (S1–S3). Compared with the parent molecule pDPA-DBTP, the as-designed HTMs S1–S3 exhibit better performance with large Stokes shifts, small exciton binding energy, better stability, good solubility and higher hole mobility. The values of hole mobility for the molecules (S1–S3) are 1.07 × 10⁻², 1.47 × 10⁻² and 1.60 × 10⁻¹ cm² V⁻¹ s⁻¹, respectively. These results provide useful information and demonstrate that adjusting the electron-deficiency of π-bridge units in bis(4-methoxyphenyl)amine-based HTMs is an efficient approach to control the properties for improving the performance of HTMs in PSC applications. Moreover, the designed S1–S3 HTMs can act as promising candidates for providing high efficiency in PSC applications.

Spiro-OMeTAD has been playing an indispensable role in highly efficient perovskite solar cells (PSCs). However, a long air oxidation process is usually required, which is harmful to the device stability. Herein, a simple and efficient doping strategy is proposed by adding a low-cost organic oxidant (2-iodoxybenzoic acid, IBX) to spiro-OMeTAD. IBX can accelerate the oxidation process of spiro-OMeTAD, thus effectively improving the conductivity and hole mobility of hole transport layers. What's more interesting, it is found that the reduction product of IBX, 2-iodobenzoic acid, can passivate the I vacancies and uncoordinated Pb²⁺ defects on the surface of perovskite, thereby inhibiting nonradiative recombination. Ultimately, the IBX-treated PSCs achieved a power conversion efficiency of 22.45%, superior to that of the pristine device (20.42%). In addition, the stability of the IBX-based device is improved. Overall, the cost-effective, facile and dual functional doping strategy is quite promising in improving the efficiency and stability of PSCs.