Perylene Diimide‐based Non‐fullerene Acceptors With A‐D‐A′‐D‐A Architecture For Organic Solar Cells

Abstract

The vinylene‐bridged helical PDI dimer (PDI2) has been an alternative PDI building block for non‐fullerene acceptor (NFAs). However, the development of PDI2 derivatives still lag behind, and most of PDI2 derivatives based organic solar cells (OSCs) only achieved a moderate power conversion efficiencies (PCE) of less than 8%. In this contribution, an acceptor‐donor‐acceptor‐donor‐acceptor (A‐D‐A’‐D‐A) architecture was introduced to facilitate the improvement of photovoltaic properties. Two acceptors named diIDTIC‐PDI2 and diFIDTIC‐PDI2 were designed and synthesized, in which a PDI2 moiety flanked with two indacenodithiophene (IDT) units was employed as the D‐A’‐D core and 2‐(3‐oxo‐2,3‐dihydro‐1H‐inden‐1‐ylidene)malononitrile (IC) or fluorinated IC (IC2F) acted as terminal groups, respectively. The photovoltaic performances of these two acceptors were explored using PM1 as the electron donor. Compared to diIDTIC‐PDI2, the fluorinated diFIDTIC‐PDI2 based OSCs obtained enhanced photovoltaic performance with the best PCE of 9.77%, a VOC of 0.957 V, JSC of 13.58 mA cm−2 and FF of 75.1%. These results illustrate that engineering terminal groups is a robust strategy of enhancing the efficiency of PDI based acceptors with A‐D‐A’‐D‐A architecture.

Bay-Substitution of Perylene Bisimides with Bidentate Nucleophiles: The Case of Aryloxide Anions

“…Some years ago, Wurthner and colleagues reported an unusual case of bay-substitution in which a sterically congested phenoxide anion reacts with PBI through a carbon nucleophilic substitution reaction, resulting in C-coupled biarenes. 22 The study focused on the reaction between a dibrominated PBI and 2,6-di-tert-butylphenol (2,6 DTBP), exclusively leading to C− C coupling products in good yields (Scheme 1b). Despite the conditions resembling those of S N Ar reactions, the observed regioselectivity was explained through an unimolecular radical nucleophilic substitution (S RN 1) mechanism.…”

“…Perylene bisimides (PBIs) are one of the most versatile and extensively employed groups of functional dyes. Their distinctive properties, including remarkable electron affinities, near-unity fluorescence quantum yields, thermal and photochemical robustness, make them an integral part in a wide range of applications in areas such as photocatalysis, organic photovoltaics, − sensing, organic field effect transistors, and OLEDs. , While chemical modifications at the imide position of PBIs typically affect their solubility, , the introduction of substituents at the bay and ortho positions (Scheme a) offers an efficient means to finely tune the optical and redox properties of these dyes. , Furthermore, covalent modifications in the bay region often induce a twisted conformation of the π-conjugated framework, significantly influencing the molecular arrangement in condensates, which is important for their application in the development of novel functional materials. , …”