A Pyrene‐Fused Dimerized Acceptor for Ternary Organic Solar Cells with 19% Efficiency and High Thermal Stability

Abstract

A pyrene‐fused dimerized electron acceptor has been successfully synthesized and subsequently incorporated as the third component in ternary organic solar cells (OSCs). Diverging from the traditional dimerized acceptors with a linear configuration, this novel electron acceptor displays a distinctive “butterfly‐like” structure, comprising two Y‐acceptors as wings fused with a pyrene‐based backbone. The extended π‐conjugated backbone and the electron‐donating nature of pyrene enable the new acceptor to show low solubility, elevated glass transition temperature (Tg), and low‐lying frontier energy levels. Consequently, the new dimerized acceptor seamlessly integrates as the third component into ternary OSCs, enhancing electron transporting properties, reducing non‐radiative voltage loss, and elevating open‐circuit voltage. These merits have enabled the ternary OSCs to show an exceptional efficiency of 19.07%, a marked improvement compared to the 17.6% attained in binary OSCs. More importantly, the high Tg exhibited by the pyrene‐fused electron acceptor helps to stabilize the morphology of the photoactive layer thermal‐treated at 70 °C, retaining 88.7% efficiency over 600 hours. For comparison, binary OSCs experience a decline to 73.7% efficiency after the same duration. These results indicate that the “butterfly‐like” design and the incorporation of a pyrene unit is a promising strategy in the development of dimerized electron acceptors for OSCs.

Dimerized Nonfused Electron Acceptor Based on a Thieno[3,4-c]pyrrole-4,6-dione Core for Organic Solar Cells

“…27−37 These new acceptors possess enhanced T g s compared to that of their single counterparts, 38,39 and the PCEs of OSCs based on oligomerized Yacceptors have exceeded 19% with good light-soaking stability and thermal stability. 40 However, oligomerized fused electron acceptors (OFEAs) usually have critical issues, such as high product costs due to the complex synthesis step and low yields of single FREAs. 16 As an alternative, partially or completely nonfused electron acceptors (NFEAs) have emerged as a costeffective alternative.…”

“…Oligomers are composed of repeated molecule units, combining the benefits of both small molecules and polymers, including well-defined structures, great solution processability, and good batch-to-batch reproducibility . Recently, a series of oligomerized Y-acceptors emerged as noteworthy candidates for OSCs (Figure a). − These new acceptors possess enhanced T g s compared to that of their single counterparts, , and the PCEs of OSCs based on oligomerized Y-acceptors have exceeded 19% with good light-soaking stability and thermal stability . However, oligomerized fused electron acceptors (OFEAs) usually have critical issues, such as high product costs due to the complex synthesis step and low yields of single FREAs .…”

Brominated Quaternary Ammonium Salt-Assisted Hybrid Electron Transport Layer for High-Performance Conventional Organic Solar Cells

“…Organic solar cells (OSCs) have garnered considerable attention due to their merits including being flexible, lightweight, and solution-processable for manufacturing. − Recently, the maximum power conversion efficiency (PCE) of single-junction OSCs has approached nearly 20%, which is attributed to the emergence of nonfullerene photovoltaic materials together with the continuous optimization of device engineering. − A typical OSC is structured by two electrodes sandwiching a photoactive layer with hole (HTL) and electron (ETL) transport layers between their interfaces, in which the photoactive layer determines light-harvesting and free-carrier production, while the HTL/ETL play a vital role in carrier transport and long-term operational stability. − …”

Hybrid Nonfused Electron Acceptors with Perylene Diimide Pendants for Organic Solar Cells

“…developed a fused-ring electron acceptor ITIC with an A–D–A-type structure, which showed several advantages, including tunable absorption spectra to the near-infrared region, suitable energy levels, unique crystalline properties, and high charge carrier mobilities . This enables the study of OSCs to enter into a nonfullerene era. − Subsequently, in the year of 2019, the fused electron acceptor Y6 and its derivatives boosted the PCEs of OSCs to over 19%. ,− …”