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Because of its high conductivity, wide bandgap, and excellent photostability, tin oxide (SnO2) has long been recognized as an electron‐transport layer (ETL) in organic solar cells (OSCs). However, the energy‐level mismatch between the work function (WF) of SnO2 and the lowest unoccupied molecular orbital level of Y‐series nonfullerene acceptors (NFAs), along with the abundance of surface defects on SnO2, have limited its widespread application as ETLs in OSCs. Herein, a novel approach utilizing urea‐functionalized polyethyleneimine (PEI) materials called u‐PEIs for modifying SnO2 is introduced. This modification, which serves dual purposes of WF modulation and surface‐defect passivation, can mitigate the energy barriers of SnO2/Y‐series NFA and increase the conductivity of the SnO2 film. PM6:Y6‐based OSCs with u‐PEI‐modified SnO2 (SnO2:u‐PEI) ETLs exhibit a remarkable efficiency of 16%, which significantly exceeds that (13.5%) achieved with bare SnO2‐based OSCs, along with outstanding photo‐ and thermal stability. This study confirms the efficacy of urea‐functionalized PEI for efficient and stable OCSs, paving the way for SnO2 applications. [ABSTRACT FROM AUTHOR]

Organometal halide perovskites (OHPs) have become potential candidates for high‐efficiency photoelectrodes for use in photoelectrochemical (PEC) water splitting. However, undesired losses, such as the non‐radiative recombination of photogenerated carriers and sluggish reaction kinetics of PEC water splitting, are the main limitations to achieving maximum efficiency for OHP‐based photoelectrodes. Herein, high‐efficiency OHP‐based photoanodes with a rational design that suppresses the undesired losses is reported. As a rational design for OHP‐based photoanodes, the defect‐passivated electron transport layers effectively suppress the undesired recombination of photogenerated carriers from the OHP layers. In addition, Fe‐doped Ni3S2 with a high catalytic activity promotes the reaction kinetics of PEC water oxidation, thereby suppressing the undesired losses at the interface between the OHP photoanodes and electrolytes. The fabricated Fe‐doped Ni3S2/Ni foil/OHP photoanodes exhibit a remarkable applied bias photon‐to‐current efficiency of 12.79%, which is the highest of the previously reported OHP‐based photoanodes by suppressing undesired losses. The strategies for achieving high‐efficiency OHP‐based photoanodes provide insights into the rational design of photoelectrodes based on OHPs. [ABSTRACT FROM AUTHOR]

Herein, we design and characterize 9-heterocyclic ring non-fullerene acceptors (NFAs) with the extended backbone of indacenodithiophene by cyclopenta [2,1-b:3,4-b'] dithiophene (CPDT). The planar conjugated CPDT donor enhances absorption by reducing vibronic transition and charge transport. Developed NFAs with different end groups shows maximum absorption at approximately 790–850 nm in film. Because of the electronegative nature of the end-group, the corresponding acceptors showed deeper LUMO energy levels and red-shifted ultraviolet absorption. We investigate the crystallinity, film morphology, surface energy, and electronic as well as photovoltaic performance. The organic photovoltaic cells using novel NFAs with the halogen end groups fluorine or chlorine demonstrate better charge collection and faster exciton dissociation than photovoltaic cells using NFAs with methyl or lacking a substituent. Photovoltaic devices constructed from m-Me-ITIC with various end groups deliver power conversion efficiencies of 3.6–11.8%. [ABSTRACT FROM AUTHOR]

Non-fullerene acceptors (NFAs) have been crucial in improving the efficiency of organic solar cells (OSCs) due to their attractive properties, such as strong light-harvesting ability, easily tunable energy levels, and high crystallinity. Nevertheless, general NFAs have limited light absorption, and studies on the design of NFAs that can absorb a broad range of the solar spectrum and that offer complementary absorption to that of donors should be conducted. Because selenium, a chalcogen element, can induce strong intermolecular Se⋯Se interactions, planarity, and extended effective conjugated length in OSC materials, NFAs with selenium usually exhibit redshifted absorption. Here, we synthesized a series of selenium-containing non-fullerene acceptors with different inner alkyl chain lengths, named Se-Y6-BO (2,2'-((2Z, 2′Z)-((12,13-bis(2-butyloctyl)-3,9-dinonyl-12,13-dihydroselenopheno[2″,3'':4′,5']thieno[2′,3':4,5]pyrrolo[3,2-g]selenopheno[2′,3':4,5]thieno [3,23,2-b] [1,2,5]thiadiazolo [3,43,4-e]indole-2,10-diyl)bis(methanylylidene))bis(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile) and Se–Y6-HD (2,2'-((2Z, 2′Z)-((12,13-bis(2-hexyldecyl)-3,9-dinonyl-12,13-dihydroselenopheno[2″,3'':4′,5']thieno[2′,3':4,5]pyrrolo[3,2-g]selenopheno[2′,3':4,5]thieno [3,23,2-b] [1,2,5]thiadiazolo [3,43,4-e]indole-2,10-diyl)bis(methanylylidene))bis(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile). The optical absorption of two selenium-containing NFAs was redshifted compared with that of Y6 due to the effect of selenium atoms in the backbone. The PM6:Se-Y6-BO-based devices achieved a power conversion efficiency (PCE) of 13.8% with an open-circuit voltage (V OC) of 0.81 V, short-circuit current density (J SC) of 24.4 mA cm−2, and a fill factor of 0.70. Similarly, the OSCs based on PM6:Se–Y6-HD achieved a PCE of 13.6% and a J SC of 23.7 mA cm−2. • A series of selenium-substituted non-fullerene acceptors with side chain engineering were synthesized for organic photovoltaics. • Two new selenium-containing non-fullerene acceptors, named Se-Y6-BO and Se–Y6-HD, achieved the best power conversion efficiency of 13.8% and 13.6%, respectively. [ABSTRACT FROM AUTHOR]