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Solution-processed organic solar cells (OSCs) have great promise for next-generation solar energy conversion technologies. Innovative acceptors are constantly being designed to improve device efficiency. In this work, we designed and synthesized a series of A–π–D–π–A type non-fullerene acceptor (NFA) molecules, named IB-TOT, IB-TOM, IB-IOO, and IB-IOM for their applications in OSCs. All molecules showed high thermal stability, broad photoabsorption, and relatively lower highest occupied molecular orbital (HOMO) energy levels from −5.48 eV to −5.58 eV. The optimized OSCs based on these NFAs and PTB7-Th donor deliver power conversion efficiencies (PCEs) of 8.19%, 5.50%, 2.42%, and 3.10% for IB-TOT, IB-TOM, IB-IOO, and IB-IOM molecules, respectively. The higher PCE of IB-TOT-based OSCs is attributed to their excellent miscibility and superior interpenetrating network morphology compared to the other three compounds. These results demonstrate that using the 3-ethylrhodanine acceptor unit to construct the NFA molecule is a successful approach for outstanding achievement in OSCs. • Four IDT-based NFA molecules were designed and synthesized. • The impact of various end-groups on device performance was fully discussed. • An empirical relationship between the end groups was established. • The best-performing OSCs achieved a maximum PCE of 8.19%. • The work promotes future OSC performance enhancement. [ABSTRACT FROM AUTHOR]

• Poly(styrene- co -acrylic acid) nanoparticles are synthesized via emulsion polymerization. • Poly(styrene- co -acrylic acid) nanoparticle films are applied as antireflection layers. • The antireflective coatings increase the light absorption efficiency of the solar cells. • Specifically, the efficiency of the solar cell is improved due to increased photocurrent generation. A simple method is described herein for the preparation of highly transparent antireflection (AR) coatings based on polymeric nanoparticles (NPs) for efficient organic solar cells. The NPs based on poly(styrene- co -acrylic acid) (PS- co -PAA) are synthesized via a straightforward emulsion polymerization process, and air void-containing AR films are deposited onto the glass sides of organic solar cells via spin-casting of the NP solution. Various NP sizes ranging from 42 to 86 nm are used to provide a variety of pore fractions and refractive indices. The AR film with an average particle size of 86 nm is shown to increase the normal-incident 595-nm light transmittance from 92.0 to 98.9%. The AR coatings on solar cells are beneficial for the light absorption of the photoactive layers, thus resulting in enhanced short-circuit current densities of up to ∼26.8 mA cm-2. The power conversion efficiency of the device with the optimum AR coating is increased to 12.8% compared to that of non-AR device (12.0%). This work represents a simple strategy for developing high-performance solar cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • We report a cyano-containing conjugated polymer, PBDT2CNBT, which functionalizes perovskite crystalline domains for defect passivation and charge carrier extraction. • The cyano groups can effectively passivate such defects by achieving strong interactions between the conjugated polymer and perovskite components. • PBDT2CNBT polymer infiltrates the grain boundaries of the perovskite crystals, making the intrinsically detrimental grain boundary beneficial for defect-free properties and enhances charge collection. The grain boundaries in polycrystalline metal-halide perovskite films contain numerous defects, which contribute to performance loss and degradation in perovskite solar cells. In this study, we report a cyano-containing conjugated polymer, composed of benzodithiophene and bicyanobenzothiadiazole (PBDT2CNBT), that functionalizes perovskite crystalline domains for defect passivation and charge carrier extraction. We demonstrate that cyano groups can effectively passivate these defects through strong interactions between the conjugated polymer and perovskite components. The PBDT2CNBT polymer not only modifies the perovskite film surface but also infiltrates the grain boundaries during perovskite crystallization. Notably, these conjugated polymers create favorable energy band bending at the boundary interface between the perovskite and conjugated polymer, enhancing charge separation and collection through grain boundaries by forming a cascade energy level structure. Consequently, we show that PBDT2CNBT transforms the intrinsically detrimental grain boundary into a beneficial feature for defect-free properties and improved charge collection. These advantages directly contribute to achieving high power conversion efficiencies of up to 22.9% and enhanced light, humidity, and thermal stability in perovskite solar cells. This study offers a novel strategy for developing multifunctional conjugated polymers for next-generation perovskite optoelectronics. [ABSTRACT FROM AUTHOR]

• Polymer donors are suitable for semi-transparent organic solar cells. • PL1 and PL2 can selectively absorb the light in NIR region. • The difference of steric structure of PL1 and PL2 affects device parameters. • PL2-based semi-transparent device presents 40.4% of AVT and 4.00% of LUE. Semi-transparent organic solar cells (ST-OSCs) have attracted significant attention for various applications such as building-integrated photovoltaics and smart window technologies. Although various low-band gap non-fullerene acceptors have been developed, near-infrared (NIR) absorbing polymeric donors have been rarely reported for highly efficient ST-OSCs. In this study, we synthesize cyclopentadithiophene (CPDT) core-based NIR-absorbing polymer donors, PL1 and PL2. These polymer donors show strong NIR absorption capabilities with high transmittance in visible wavelength region and deep-lying HOMO levels for cascade energy level alignment with low-bandgap non-fullerene acceptors. The opaque device with PL2 and PCBM exhibits higher power conversion efficiency of 11.62% than that of the device with PL1 (PCE: 7.54%) due to lower charge-carrier recombination loss and balanced charge-carrier mobilities. Most significantly, incorporation of PL2 into ST-OSCs results in a PCE of 9.91 %, average visible transmittance of 40.4 % and light utilization efficiency (LUE) of 4.00 %. This work achieves the one of the highest LUE in ST-OSCs based on new NIR-absorbing polymer donors. [ABSTRACT FROM AUTHOR]