Despite their minimal HOMO energy level offset promising power conversion efficiencies up to 13.54% have been recorded for ternary organic solar cells using coumarin-based molecular donors and fullerene-free acceptors.

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The small-molecule-based donor/acceptor blend is an important component in bulk-heterojunction organic solar cells (OSCs). Although a variety of small-molecule donors have been developed in recent years, only a few of them have reached efficiencies over 15% using fullerene-free acceptors in OSCs. Therefore, it is important to develop high-performing molecular donor materials with ideal molecular orbital energy levels, complementary absorption to the acceptors, and good charge-transporting character. Herein, the design and development of two wide band gap functional coumarin-based donor materials C1-CN and C2-CN are presented, which are synthesized efficiently using readily accessible starting materials, an important criterion for the realization of cost-effective large area OSCs. The associated effect of excellent optoelectronic and thermal properties and frontier orbital energy levels enabled the application of the synthesized donors in solution-processed fullerene-free OSCs. Ternary OSCs fabricated with C1-CN:DBTBT-IC:Y6 displayed efficiencies up to 15.28%, one of the highest values reported for all-small-molecule OSCs with a low energy loss of 0.43 eV.

A purified alkaline thermotolerant bacterial lipase from Bacillus coagulans BTS-3 was immobilized on nylon-6 matrix activated by glutaraldehyde. The matrix showed $ 70% binding efficiency for lipase. The bound lipase was used to perform transesterification in n-heptane. The reaction studied was conversion of vinyl acetate and butanol to butyl acetate and vinyl alcohol. Synthesis of butyl acetate was used as a parameter to study the transesterification reaction. The immobilized enzyme achieved $ 75% conversion of vinyl acetate and butanol (100 mmol/L each) into butyl acetate in n-heptane at 558C in 12 h. When alkane of C-chain lower or higher than n-heptane was used as an organic solvent, the conversion of vinyl acetate and butanol to butyl acetate decreased. During the repetitive transesterification under optimal conditions, the nylon bound lipase produced 77.6 mmol/L of butyl acetate after third cycle of reuse.

The choice of molecular material plays a crucial role in improving the performance of organic solar cells. Herein, two coumarin‐based small molecules are designed and synthesized in which the π‐system is extended by the introduction of double bonds. The molecules are differed by the attachment of central acceptor units. The replacement of the carbonyl group in C3 by the dicyanomethylene unit in C3–CN red‐shift the absorption, reduced the energy gap, and stabilized the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. When blended with a complementary absorbing all‐fused acceptor F13, the binary devices using C3 donor delivered a power conversion efficiency (PCE) of 11.09%. In contrast, C3–CN:F13‐based binary device displayed an impressive PCE of 14.84% due to the obvious increase in all open circuit voltage, short circuit current density, and fill factor values. The inclusion of CN group to the molecular backbone induces a tighter intermolecular packing, which is beneficial for the charge transport properties. The study demonstrates that the subtle modification in conjugation length and tuning of the energy level by the proper choice of acceptor could be a promising way to improve the device's performance.