3‐Benzofuranone Based Asymmetric Guest Nonfullerene Acceptors for Reduced Voltage Loss

Why It Matters

The breakthrough pushes organic photovoltaic efficiency past the 19% threshold while enhancing stability, accelerating the technology’s commercial viability in flexible and lightweight energy markets.

Key Takeaways

• 3‑benzofuranone derivatives act as guest acceptors in PM6:BTP‑eC9
• Adding 0.03 wt% ZHY compounds reduces π‑π stacking distance
• Ternary cells achieve 19.5% efficiency, up from 18.3% binary
• Enhanced crystallinity improves charge mobility and lowers recombination
• Monofluorination further boosts exciton lifetime and stability

Pulse Analysis

Organic photovoltaic (OPV) technology has long been hampered by a trade‑off between power conversion efficiency and long‑term stability. While perovskite cells have breached the 25% barrier, OPVs remain attractive for flexible, lightweight applications, provided they can close the voltage‑loss gap that typically drags efficiencies below 20%. Nonfullerene acceptors (NFAs) have emerged as the primary route to higher open‑circuit voltages, yet many designs still suffer from suboptimal molecular packing and non‑radiative recombination. Recent research therefore focuses on fine‑tuning the acceptor’s end groups to manipulate solid‑state order without sacrificing processability.

The study from Wiley’s Advanced Energy Materials introduces a series of asymmetric NFAs—ZHY1, ZHY2 and ZHY3—built on a 3‑benzofuranone core and its monofluorinated analogues. By incorporating just 0.03 wt% of these guest molecules into the benchmark PM6:BTP‑eC9 blend, the authors observed a measurable contraction of the π‑π stacking distance and an extension of the crystalline correlation length for both donor and acceptor phases. These structural refinements translate into faster charge separation, longer exciton lifetimes, higher charge mobilities, and a marked reduction in both monomolecular and bimolecular recombination pathways.

The performance payoff is striking: the ternary device reaches a certified 19.5% power conversion efficiency, eclipsing the 18.3% of the binary reference while also delivering improved thermal and photochemical stability. Such gains narrow the gap between OPVs and incumbent thin‑film technologies, positioning asymmetric 3‑benzofuranone NFAs as a viable platform for commercial‑scale modules. Future work will likely explore scaling the guest‑addition strategy, integrating it with roll‑to‑roll coating, and extending the molecular design to other fluorinated heterocycles, accelerating the path toward market‑ready, high‑efficiency organic solar panels.