Fluorinated solid additives have been designed to increase the π–π stacking of non-fullerene acceptor BTP-4F, leading to increased efficiency from 15.2% to 16.5% of PBDB-T-2F:BTP-4F binary solar cells with excellent stability.

The molecular aggregation of nonfullerene acceptors (NFA) can significantly affect the light absorption, charge generation, and power conversion efficiency (PCE) of organic solar cells (OSCs). In this work, we demonstrate the regulation of J-aggregation of COi8DFIC NFA toward near-infrared absorption via solvent additives 1,8diiodooctane (DIO), diphenyl ether (DPE), and 1-chloronaphthalene (CN). Molecular dynamics simulations reveal preferential interaction of DIO with the alkyl side chains of COi8DFIC, endowing side-chains with the flexibility to adjust conformations to promote the formation of "Ato-D" type J-aggregation among the COi8DFIC backbone, resulting in a significant red-shift of absorbance toward the near-infrared region. The enhanced J-aggregation via π−π stacking, evidenced by grazing-incidence wide-angle X-ray scattering, constructs threedimensional charge transport channels at the molecular level to facilitate charge transport. The presence of 0.5 vol % DIO molecules, which is most effective among all three additives, boosts the maximum achievable PCE of CF cast PTB7-Th:COi8DFIC OSCs from 8.5% to 12.9%. Our results provide a new concept to enhance the efficiency of OSCs via dedicated control of molecular aggregations of nonfullerene acceptors.

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Inorganic perovskite solar cells (PSCs) have witnessed great progress in recent years due to their superior thermal stability. As a representative, CsPbI 2 Br is attracting considerable attention as it can balance the high efficiency of CsPbI 3 and the stability of CsPbBr 3 . However, most research employs doped charge transport materials or applies bilayer transport layers to obtain decent performance, which vastly complicates the fabrication process and scarcely satisfies the commercial production requirement. In this work, all‐layer‐doping‐free inorganic CsPbI 2 Br PSCs using organic ligands armored ZnO as the electron transport materials achieve an encouraging performance of 16.84%, which is one of the highest efficiencies among published works. Meanwhile, both the ZnO‐based CsPbI 2 Br film and device show superior photostability under continuous white light‐emitting diode illumination and improved thermal stability under 85 °C. The remarkable enhanced performance arises from the favorable organic ligands (acetate ions) residue in the ZnO film, which not only can conduce to maintain high crystallinity of perovskite, but also passivate traps at the interface through cesium/acetate interactions, thus suppressing the photo‐ and thermal‐ induced perovskite degradation.

The insufficient phase separation between polymer donors and non-fullerene acceptors (NFAs) featuring with low-structural orders disrupts efficient charge transport and increases charge recombination, consequently limits the maximum achievable power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, an NFA IT-M has been added as the third component into the PBDB-T:m-INPOIC OSCs, and is shown to effectively tune the phase separation between donor and acceptor molecules, although all components in the ternary system exhibit low degrees of structural orders. The incorporation of 10 wt% IT-M into a PBDB-T:m-INPOIC binary host blend appreciably increases the length scale of phase separation, creating continuous pathways which increase and balance charge transport. This leads to an enhanced photovoltaic performance from 12.8% in the binary cell to 13.9% for the ternary cell with simultaneously improved open-circuit voltage, short-circuit current and fill factor. This work highlights the beneficial role of ternary components in controlling the morphology of the active layer for high performance OSCs.