Additive engineering can precisely regulate the bulk-heterojunction active layer morphology with ideal domain size and purity, playing a critical role in development of organic solar cells (OSCs). Herein, two solid additives, 1,4-dichlorobenzene (DCB) and 1-chloro-4-iodobenzene (CIB), with low melting point (mp.) of ≈52 °C, are investigated comprehensively with comparison to 1,4-diiodobenzene (DIB, mp. 131 °C). After spin-coating, DIB residue is found in the as-cast PM6:BTP-eC9 based blend film, whereas the DCB and CIB are completely removed during the spin-coating, showing in situ removable properties that enable convenient processing. In OSCs, the DCBand CIB-processed active layers afford power-conversion efficiencies (PCEs) of 18.2% and 18.4%, respectively, all higher than that of 17.8% for DIB. Among the three solid additives, the CIB is most effective in enhancements of absorption coefficients of the donor and acceptor, affording fast and more balanced carrier transports, and suppressing recombination. Of particular note, the CIB can provide some universality as an in situ removable solid additive, based on its elevations of PCEs for several binary and PM6:D18-Cl:L8-BO ternary active layers. Impressively, a prominent PCE of 19.1% with a remarkable fill factor of 81.1% is achieved for the CIB-processed ternary active layer. This work demonstrates the potential of in situ removable solid additive engineering in high-efficiency OSCs.

Near‐infrared organic photodetector of high sensitivity is essential for various remote sensing applications. In this work, a new simple fused‐ring acceptor “NTQ” with a narrow optical bandgap of 1.11 eV is designed and synthesized to demonstrate the first near‐infrared organic photodetector example featuring a non‐fused A‐D‐A′‐D‐A molecular framework. The optimized geometry of NTQ exhibits high planarity and the relevant pristine film shows high electron mobility of 1.51 × 10−4 cm2 V−1 s−1. Moreover, the PTB7‐Th:NTQ blend can achieve relatively high and balanced hole/electron mobility even though the photo‐active layer thickness is up to 320 nm. The NTQ‐based devices exhibit high shot‐noise‐limited specific detectivity (Dsh*) of 3.72 × 1012 Jones at 1000 nm under the bias of –0.1 V and a board Dsh* response over 1012 Jones from 320 to 1070 nm. Furthermore, the device exhibits fast averaged rise and fall times of 2.02 and 2.42 µs, respectively. This work demonstrates that molecular engineering with the A‐D‐A′‐D‐A framework can endow near‐infrared photo‐active materials with high‐performing photodetectors for wide applications.

Non-fullerene acceptors (NFAs) carrying a 1,1-dicyanomethylene-3-indanone (IC) end-group are the most powerful ones to boost the power conversion efficiency of organic solar cells (OSCs). However, the well-known Knoevenagel condensation of the mono-halogenated IC end-group will result in an NFA isomeric effect, a chemical issue that needs to be addressed. Herein, facile preparations and separations of three well-defined mono-brominated isomers BTzIC-2Br-δ, BTzIC-2Br-γ, and BTzIC-2Br-δγ via column chromatography with a well-chosen mixing solvent were demonstrated for Knoevenagel condensation, and their structures were verified by NMR spectra and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) mass spectra. It is the first time that an asymmetric isomer BTzIC-2Br-δγ is reported, and the regioisomeric effect on optoelectronic properties can be investigated based on all three isomers. Moreover, the single-crystal structure was successfully achieved for the symmetric molecule BTzIC-2Br-γ. With benzodithiophene (BDT)-free PFBT4T-T20 as an easily accessible and low-cost polymer donor, the three isomers could show differentiated device performances, with a power conversion efficiency order of BTzIC-2Br-γ (16.00%) > BTzIC-2Br-δγ (15.81%) > BTzIC-2Br-δ (15.29%). The best efficiency of 16.00% achieved with BTzIC-2Br-γ is among the highest ones for binary OSCs based on the low-cost BDT-free donors. The facile and complete synthesis of isomeric NFAs with mono-halogenated IC end-groups would promote the elucidation of the structure–property relationship.

Photoactive materials comprising a siloxane-terminated side chain could enable active layers with high humidity tolerance and maintain high efficiency.

Lithium–sulfur (Li-S) batteries with high energy density, environmental friendliness, and low cost have still suffered from the short cycle life due to the shuttle effect of the dissoluble polysulfide intermediates. In this work, a hybrid host comprising ceric dioxide (CeO2) and covalent organic frameworks (COFs) was developed for the sulfur cathode. The hybrid host of CeO2/COFs manifests strong interaction with the polysulfide. Moreover, the polar interface of CeO2 and the highly 2D ordered structure of COFs endow good electrochemically catalytic activity, which accelerates the redox reaction and restrains the shuttle effect. Owing to the chemical and physical adsorption surface, the hybrid host of CeO2/COFs demonstrates a high initial capacity (1384 mAh g–1) and low decay rate (0.1%) at 0.5C. Collectively, the in situ hybrid strategy has high potential in elevating the performance of Li-S batteries.