Facilitating charge transfer via a Semi-Coherent Fe(PO3)2-Co2P2O7 heterointerface for highly efficient Zn-Air batteries.

Developing reversible oxygen electrodes for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for achieving high-performance rechargeable Zn-air batteries (ZABs). This study introduced an nitrogen-doped carbon confined with a semi-coherent Fe(PO3)2-Co2P2O7 heterojunction for bifunctional oxygen electrocatalysis. This nanocomposite yielded an ORR half-wave potential of 0.908 V and an OER overpotential of 291 mV at 10 mA/cm2. ZABs incorporating this catalyst yielded impressive performance, including a peak power density of 203 mW/cm2, a specific capacity of 737 mAh/gZn, and promoted stability. Both experimental and theoretical simulations demonstrated that the unique electric field between Fe(PO3)2 and Co2P2O7 promoted efficient charge transport across the heterointerface. This interaction likely modulated the d-band center of the heterojunction, expedite the desorption of oxygen intermediates, thus improving oxygen catalysis and, consequently, ZAB performance. This work illustrates a significant design principle for creating efficient bifunctional catalysts in energy conversion technologies.

Highly Conductive and Solution-Processable n-Doped Transparent Organic Conductor.

Transparent conductors (TCs) play a vital role in displays, solar cells, and emerging printed electronics. Here, we report a solution-processable n-doped organic conductor from copper-catalyzed cascade reactions in the air, which involves oxidative polymerization and reductive doping in one pot. The formed polymer ink is shelf-stable over 20 days and can endure storage temperatures from -20 to 65 °C. The optimized n-doped thin-film TC exhibits a low sheet resistance of 45 Ω/sq and a high transmittance (T550 > 80%), which can rival indium tin oxide. The transparent organic conductor exhibits excellent durability under accelerated weathering tests (85 °C/85% RH). Furthermore, the n-doped polymer film can also function as an electrode material with a high volumetric capacity. When it is paired with p-doped PEDOT:PSS, a record-high coloration efficiency is obtained in a dual-polymer electrochromic device.

Tetracyanocyclopentadienide-Based Stable Poly(aromatic) Anions.

Polyelectrolytes, a class of polymer with ionized functional groups in their repeating units, are widely used in various applications. Many ionized groups have been incorporated into polyelectrolytes, but aromatic anions are rarely investigated. Here, we first successfully incorporate a stable tetracyanocyclopentadienide (TCCp) aromatic anion into polynorbornene (PNb)-based electrolytes (PNb-TCCp) through ring-opening metathesis polymerization (ROMP) with controllable molecular weight and low polydispersity. PNb-TCCp shows a high ionic conductivity of 4.5 × 10-5 S/cm in thin films. Due to its highly stable aromatic anion groups and favorable interactions with aromatic cations, it could improve thermal stability of doped conjugated polymers. Pairing with doped poly(3,4-ethylenedioxythiophene) (PEDOT) through salt metathesis, the generated poly ion complex PEDOT:PNb-TCCp retains its conductivity up to 180 °C.

Fused Tris(thienothiophene)-Based Electron Acceptor with Strong Near-Infrared Absorption for High-Performance As-Cast Solar Cells.

A fused tris(thienothiophene) (3TT) building block is designed and synthesized with strong electron-donating and molecular packing properties, where three thienothiophene units are condensed with two cyclopentadienyl rings. Based on 3TT, a fused octacylic electron acceptor (FOIC) is designed and synthesized, using strong electron-withdrawing 2-(5/6-fluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)-malononitrile as end groups. FOIC exhibits absorption in 600-950 nm region peaked at 836 nm with extinction coefficient of up to 2 × 105 m-1 cm-1 , low bandgap of 1.32 eV, and high electron mobility of 1.2 × 10-3 cm2 V-1 s-1 . Compared with its counterpart ITIC3 based on indacenothienothiophene core, FOIC exhibits significantly upshifted highest occupied molecular orbital level, slightly downshifted lowest unoccupied molecular orbital level, significantly redshifted absorption, and higher mobility. The as-cast organic solar cells (OSCs) based on blends of PTB7-Th donor and FOIC acceptor without additional treatments exhibit power conversion efficiencies (PCEs) as high as 12.0%, which is much higher than that of PTB7-Th: ITIC3 (8.09%). The as-cast semitransparent OSCs based on the same blends show PCEs of up to 10.3% with an average visible transmittance of 37.4%.

Naphthodithiophene-Based Nonfullerene Acceptor for High-Performance Organic Photovoltaics: Effect of Extended Conjugation.

Naphtho[1,2-b:5,6-b']dithiophene is extended to a fused octacyclic building block, which is end capped by strong electron-withdrawing 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile to yield a fused-ring electron acceptor (IOIC2) for organic solar cells (OSCs). Relative to naphthalene-based IHIC2, naphthodithiophene-based IOIC2 with a larger π-conjugation and a stronger electron-donating core shows a higher lowest unoccupied molecular orbital energy level (IOIC2: -3.78 eV vs IHIC2: -3.86 eV), broader absorption with a smaller optical bandgap (IOIC2: 1.55 eV vs IHIC2: 1.66 eV), and a higher electron mobility (IOIC2: 1.0 × 10-3 cm2 V-1 s-1 vs IHIC2: 5.0 × 10-4 cm2 V-1 s-1 ). Thus, IOIC2-based OSCs show higher values in open-circuit voltage, short-circuit current density, fill factor, and thereby much higher power conversion efficiency (PCE) values than those of the IHIC2-based counterpart. In particular, as-cast OSCs based on FTAZ: IOIC2 yield PCEs of up to 11.2%, higher than that of the control devices based on FTAZ: IHIC2 (7.45%). Furthermore, by using 0.2% 1,8-diiodooctane as the processing additive, a PCE of 12.3% is achieved from the FTAZ:IOIC2-based devices, higher than that of the FTAZ:IHIC2-based devices (7.31%). These results indicate that incorporating extended conjugation into the electron-donating fused-ring units in nonfullerene acceptors is a promising strategy for designing high-performance electron acceptors.