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Isomerism heavily influences the optoelectronic properties and self-assembly behavior of compounds and subsequently affects their device performance. Herein, two pairs of isomeric perylene diimide (PDI) dimers, PDI and PDI2, were designed and synthesized. The electron-deficient 9,10-anthraquinone group was employed as the bridge, and thus, the resultant dimers exhibited an acceptor-acceptor-acceptor (A-A-A) structure. To determine the isomeric effects on the optoelectronic properties and photovoltaic performance of these dimers, their absorptivity, luminescence, and redox behavior were studied. Bulk heterojunction organic solar cells based on these four dimers were fabricated and measured. The two PDI dimers exhibited clear differences in photovoltaic performance, whereas the two PDI2 analogues showed similar power conversion efficiencies (PCEs). The PCEs of the two PDI2 dimers are much higher than those of the PDI dimers. These results illustrate that the isomeric effect of PDI dimers is much larger than that of PDI2 dimers on the device performance, and proper expansion of conjugation could improve the device performance., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Perylene diimide (PDI) is one of the most intensively studied building blocks for the construction of non‐fullerene acceptors (NFAs). In this contribution, based on combination of the direct and indirect linkage manners of PDI units at the bay position, a propeller‐shaped PDI hexamer T‐DPDI was designed and synthesized. The singly bonded PDI dimer DPDI and the benzene ring cored PDI trimer TPDI were synthesized for comparison. The photovoltaic performances of these three PDI derivatives were investigated using the commercially available PTB7‐Th as electron donor. A best power conversion efficiency (PCE) of 6.58% was obtained for T‐DPDI based organic solar cells (OSCs), which is higher than those of DPDI and TPDI based ones. The superior photovoltaic performance of T‐DPDI can be ascribed to its stronger absorption and more favorable morphology. This study presents an interesting example of improving the photovoltaic performances of PDI based NFAs by hybridizing the direct and indirect linkage manners. [ABSTRACT FROM AUTHOR]

Most high-performance organic solar cells (OSCs) are so far fabricated using halogenated solvents, which are environmentally hazardous. Therefore, it is imperative to develop high-efficiency OSCs processed by more environmentally friendly solvents. Perylene diimides (PDIs) based acceptors have become one of the most promising candidates for nonfullerene OSCs owing to their outstanding optoelectronic properties. However, PDIs-based ternary OSCs are rarely investigated, let alone the green-solvent processed ones. In this study, non-halogenated solvent processed ternary OSCs using a star-shaped helical perylene diimide (TPDI2) and ITIC as acceptors, PTB7-Th as donor, were fabricated and characterized. The best power conversion efficiency (PCE) of the ternary OSCs were 8.22%, which showed a PCE improvement over 18% comparing to the reference binary blend devices (6.95%). The PCE of 8.22% is among the highest performance reported to date for PDIs-based OSCs devices processed using non-halogenated solvent (without additives). Image 1 • Efficient helical perylene diimide based ternary organic solar cells processed with single non-halogenated solvent. • ITIC plays a vital role in improving the charge transport properties of the ternary blends. • The PCE of PDIs-based ternary OSCs processing by non-halogenated solvents achieved 8.22%. [ABSTRACT FROM AUTHOR]

Isomerism heavily influences the optoelectronic properties and self‐assembly behavior of compounds and subsequently affects their device performance. Herein, two pairs of isomeric perylene diimide (PDI) dimers, PDI and PDI2, were designed and synthesized. The electron‐deficient 9,10‐anthraquinone group was employed as the bridge, and thus, the resultant dimers exhibited an acceptor–acceptor–acceptor (A‐A‐A) structure. To determine the isomeric effects on the optoelectronic properties and photovoltaic performance of these dimers, their absorptivity, luminescence, and redox behavior were studied. Bulk heterojunction organic solar cells based on these four dimers were fabricated and measured. The two PDI dimers exhibited clear differences in photovoltaic performance, whereas the two PDI2 analogues showed similar power conversion efficiencies (PCEs). The PCEs of the two PDI2 dimers are much higher than those of the PDI dimers. These results illustrate that the isomeric effect of PDI dimers is much larger than that of PDI2 dimers on the device performance, and proper expansion of conjugation could improve the device performance. [ABSTRACT FROM AUTHOR]

The ethylene fused PDI oligomers, especially for the dimer (PDI2), have emerged as alternative building blocks to the parent PDI in constructing NFAs owing to their outstanding optoelectronic properties, twisted configurations as well as concise gram-scale synthesis. In this work, a non-fullerene acceptor (NFA) based on tetraphenylethylene (TPE) core flanked with four PDI2 units, coded as TPE-4PDI2 , was designed and synthesized. The analogue (TriPE-3PDI2) which consists of triphenylethylene (TriPE) and three PDI2 panels was synthesized for comparison. OSCs based on TPE-4PDI2 show a best PCE of 7.10%, which is much higher than that of TriPE-3PDI2 based ones. Moreover, this PCE is also higher than that of TPE-4PDI based devices (5.53%). To the best of our knowledge, the PCE of 7.10% is among the highest values for TPE-cored NFAs based OSCs. These results indicate that PDI2 is a promising building block for constructing high performance NFAs. And this work provides a facile and effective molecule-designing method to promote the PCE of PDI based non-fullerene OSCs. Image 1 • Two PDI2 based non-fullerene acceptors were designed and synthesized. • TPE-4PDI2 based devices obtained a much higher PCE of 7.10% than did TriPE-3PDI2 based OSCs. • PDI2 is a promising building block for constructing high performance NFAs. [ABSTRACT FROM AUTHOR]