No abstract

Electrochemical reactions occur on the surface of the electrode, so electrode modifications are essential for redox flow batteries (RFBs). Major works regarding electrode modifications focus on traditional RFBs like vanadium systems, but minor works stress on organic RFBs that represent a rapidly developed technology for large-scale energy storage. In this work, we employ thermal oxidation (600 °C) and investigate the effect of the heating time on a polyacrylonitrile-based carbon felt used in 2,6-dihydroxyanthraquinone (2,6-DHAQ)/K 4 Fe(CN) 6 RFBs. The structure of the carbon felt is characterized by thermogravimetric analysis, scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy methods. The electrochemical properties of 2,6-DHAQ are studied by cyclic voltammetry analysis. It is found that, when the heating time is set at 2.0 h, 2,6-DHAQ/K 4 Fe(CN) 6 RFBs exhibit a lower capacity decay rate at 0.0287% per cycle in 200 cycles, which is 3 times lower than the other cases. The results from 1 H nuclear magnetic resonance spectra unveil that the lower capacity loss is achieved by converting the byproduct anthrone back into 2,6-DHAQ at a slight cost of reducing Coulombic efficiency. Our work unambiguously demonstrates that the lifetime of anthraquinone-based RFBs can be effectively extended via thermal modification of electrodes.

A novel non-fullerene acceptor–donor–acceptor (A–D–A) structured small molecule acceptor material with fused ring N-alkyl DTP as the central donor unit and EG-2F as the terminal acceptor unit, named DTP-C17-4F, was designed and synthesized.

Because of the mismatch between the solar irradiance spectra and the photoactive layer absorption spectra, only a part of sunlight can be utilized, which fundamentally restricting the power conversion efficiency (PCE) of the polymer solar cells (PSCs). Ternary blend PSCs, with an additional third component, have become an effective approach to extend the absorption spectra and increase the mobility of the charge carriers. Herein, we select the middle band gap PBDTBDD as an electron donor and narrow band gap ITIC and wide band gap PCBM as electron acceptors to construct ternary blends for simultaneously enhancing the absorption intensity and expanding the absorption band. The optical properties, morphologies, and the charge-/energy-transfer behaviors of the ternary blends are investigated. By attentively adjusting the ratio of the third component, ITIC, the ternary PSCs demonstrate an expanded light-response region and greatly enhanced J, giving an improved overall PCE of 10.36%, much higher than that of the binary counterparts based on PBDTBDD:PCBM (6.63%) and PBDTBDD:ITIC (9.44%). These findings indicate that proper selection of donors and acceptors to construct absorption spectra-complementary ternary blend photoactive layers is an effective way to achieve high-performance PSCs.

Organic polymer solar cells (PSCs) have attracted increasing attention due to light weight, low cost, flexibility and roll‐to‐roll manufacturing. However, the limited light harvest range of the photoactive layer greatly restrains the power conversion efficiency (PCE) enhancement. In order to expand the light absorption range and further enhance the PCE of the PSCs, tandem structures have been designed and demonstrated. In tandem solar cell, the intermediate layer (IML) plays a critical role in physically and electrically connection of the two subcells. Herein, we apply titanium (diisopropoxide) bis(2,4‐pentanedionate) (TIPD) as both electrode modification layer and intermediate layer to investigate the feasibility in inverted tandem polymer solar cells. The same photoactive layers of PTB7‐Th:PC71BM are adopted in both front and rear subcells to simplify the evaluation of effectiveness of TIPD layer in tandem structures. By modulating the treatment condition of IML and the thickness of photoactive layer, efficient inverted tandem PSCs have been achieved with minimized voltage loss and excellent charge transportation, giving a best Voc of 1.54 V, which is almost two times that of the single bulk heterojunction (BHJ)‐PSC (0.78 V) and an enhanced PCE up to 8.11%.