A Designed Ladder‐Type Heteroarene Benzodi(Thienopyran) for High‐Performance Fullerene‐Free Organic Solar Cells

Abstract

To meet the imminent requirement of fullerene‐free electron acceptors, a new ladder‐type heteroarene benzodi(thienopyran) (BDTP) is designed and synthesized by embedding pyran rings in [2,2‐(2,5‐dialkyloxy‐1,4‐phenylene)dithiophene] (PDT) for organic photovoltaic (OPV) applications. Originating from the strong p–π conjugation of the oxygen atom in the pyran rings, electron‐rich BDTP results in the BDTP‐cored molecular acceptor, NBDTP, with strong intramolecular charge transfer effect. With sp3 carbons in pyran rings, NBDTP have the flexibility of targeted modification to resolve the solubility as well as the morphological tuning by handy alkyl chain attachment. As a result, the fusion of pyran rings in BDTP means that the acceptor exhibits a narrow optical band gap of 1.58 eV and a high LUMO energy level of −3.79 eV. Meanwhile, blend morphology of NBDTP‐based OPVs shows fine tunability via thermal annealing. Owing to the beneficial optical absorption, suitable energy‐level alignment, favorable molecule packing, and proper morphology, the optimized NBDTP‐based OPVs achieve a power conversion efficiency of up to 10.1%, which exemplifies the potential of utilizing molecular acceptors featuring ladder‐type heteroarenes for high‐performance OPVs.

Comparison of fluorene, silafluorene and carbazole as linkers in perylene monoimide based non-fullerene acceptors

“…S16 (ESI †). According to previous reports in the literature, 41,42 the GIWAXS images reveal a typical pattern for preferential face-on orientation.…”

Carbon–Oxygen‐Bridged Ladder‐Type Building Blocks for Highly Efficient Nonfullerene Acceptors

“…Owing to the high overall yield, gram‐scale synthesis of CO i 8 was realized. In the meantime, Zhu and co‐workers reported a similar approach for the synthesis of a pentacyclic CO‐bridged unit, BDTP (Scheme d) . In this case, the demethylation and transesterification took place simultaneously.…”

“…PBDB‐T: Ph ‐DTDP‐TIC solar cells gave a PCE of 9.21%, with a higher V oc of 0.89 V and a higher J sc of 17.31 mA cm −2 . Zhu and co‐workers reported an A–D–A acceptor, NBDTP, based on pentacyclic BDTP core unit and two 2‐(4‐oxo‐4H‐cyclopenta[ b ]thiophen‐6(5 H )‐ylidene)malononitrile end units . BDTP is similar to CO5 but with CO bonds pointing to the core.…”

Hydrogen‐Bonding Strategy to Optimize Charge Distribution of PC71BM and Enable a High Efficiency of 12.45% for Organic Solar Cells

“…In the last decade, bulk heterojunction (BHJ) organic solar cells (OSCs) have achieved rapid development due to new donor/acceptor materials, novel device structure, and optimal fabrication technology . The highest power conversion efficiency (PCE) has exceeded 12% for single‐junction binary blend OSCs up to now .…”