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Recent advances in light‐responsive materials enabled the development of devices that can wirelessly activate tissue with light. Here it is shown that solution‐processed organic heterojunctions can stimulate the activity of primary neurons at low intensities of light via photochemical reactions. The p‐type semiconducting polymer PDCBT and the n‐type semiconducting small molecule ITIC (a non‐fullerene acceptor) are coated on glass supports, forming a p–n junction with high photosensitivity. Patch clamp measurements show that low‐intensity white light is converted into a cue that triggers action potentials in primary cortical neurons. The study shows that neat organic semiconducting p–n bilayers can exchange photogenerated charges with oxygen and other chemical compounds in cell culture conditions. Through several controlled experimental conditions, photo‐capacitive, photo‐thermal, and direct hydrogen peroxide effects on neural function are excluded, with photochemical delivery being the possible mechanism. The profound advantages of low‐intensity photo‐chemical intervention with neuron electrophysiology pave the way for developing wireless light‐based therapy based on emerging organic semiconductors. [ABSTRACT FROM AUTHOR]

Non-fullerene based organic solar cells display a high initial power conversion efficiency but continue to suffer from poor thermal stability, especially in case of devices with thick active layers. Mixing of five structurally similar acceptors with similar electron affinities, and blending with a donor polymer is explored, yielding devices with a power conversion efficiency of up to 17.6%. The hexanary device performance is unaffected by thermal annealing of the bulk-heterojunction active layer for at least 23 days at 130 °C in the dark and an inert atmosphere. Moreover, hexanary blends offer a high degree of thermal stability for an active layer thickness of up to 390 nm, which is advantageous for high-throughput processing of organic solar cells. Here, a generic strategy based on multi-component acceptor mixtures is presented that permits to considerably improve the thermal stability of non-fullerene based devices and thus paves the way for large-area organic solar cells. Non-fullerene-based organic solar cells generally suffer from poor thermal stability and especially in case of devices with thick active layers. Here, the authors report hexanary blends based on multi-component acceptor mixtures with a device efficiency of 17.6% and thermally stability for 23 days at 130 °C. [ABSTRACT FROM AUTHOR]

Efficiencies of organic solar cells have practically doubled since the development of non‐fullerene acceptors (NFAs). However, generic chemical design rules for donor‐NFA combinations are still needed. Such rules are proposed by analyzing inhomogeneous electrostatic fields at the donor–acceptor interface. It is shown that an acceptor–donor–acceptor molecular architecture, and molecular alignment parallel to the interface, results in energy level bending that destabilizes the charge transfer state, thus promoting its dissociation into free charges. By analyzing a series of PCE10:NFA solar cells, with NFAs including Y6, IEICO, and ITIC, as well as their halogenated derivatives, it is suggested that the molecular quadrupole moment of ≈75 Debye Å balances the losses in the open circuit voltage and gains in charge generation efficiency. [ABSTRACT FROM AUTHOR]