High-performance polymer solar cells with efficiency over 18% enabled by asymmetric side chain engineering of non-fullerene acceptors

Abstract

Side-chain engineering has been considered as one of the most promising strategies to optimize non-fullerene small-molecule acceptors (NFSMAs). Previous efforts were focused on the optimization of alkyl-chain length, shape, and branching sites. In this work, we propose that asymmetric side-chain engineering can effectively tune the properties of NFSMAs and improve the power conversion efficiency (PCE) for binary non-fullerene polymer solar cells (NFPSCs). Specifically, by introducing asymmetric side chains into the central core, both of the absorption spectra and molecule orientation of NFSMAs are efficiently tuned. When blended with polymer donor PM6, NFPSCs with EH-HD-4F (2-ethylhexyl and 2-hexyldecyl side chains) demonstrate a champion PCE of 18.38% with a short-circuit current density (J SC ) of 27.48 mA cm −2 , an open circuit voltage (V OC ) of 0.84 V, and a fill factor (FF) of 0.79. Further studies manifest that the proper asymmetric side chains in NFSMAs could induce more favorable face-on molecule orientation, enhance carrier mobilities, balance charge transport, and reduce recombination losses.

Recent progress in organic solar cells based on non-fullerene acceptors: materials to devices

“…Since 2019, the emergence of A–DA′D–A-type FREAs, this type of acceptors has contributed to the rapid development of OSCs with PCE exceeding 18%. 11,12 Here, we will investigate the A–DA′D–A-type acceptors for high-efficiency OSCs, particularly the correlation between molecular structure and optoelectronic properties.…”

“…Fused-ring electron acceptors (FREAs), represented by SMAs, have been shown great potential for the development of OSCs and the power conversion efficiency (PCE) has been over 18%. 11–13 FREAs often contain an electron-donating fused-ring core along with two strong electron-withdrawing terminal groups coupled by a planar π-conjugated bridge, resulting in a planar molecular structure and strong intermolecular interaction. FREAs are now the most important acceptors in the development of OSCs.…”

Delicate crystallinity control enables high-efficiency P3HT organic photovoltaic cells

“…Solution-processed organic photovoltaic (OPV) cells are a clean energy technology with great commercial application prospects because of their unique features, such as high softness, light weight, colorful appearance and excellent ability to be translucent and wearable. 1–5 The past decade has witnessed dramatic advances in the performance of OPV cells and the reported power conversion efficiency (PCE) has surpassed 18%, 6–9 benefitting from the rapid development and innovation of new materials. However, the synthetic complexity and poor scalability of these new and high-efficiency materials result in considerably high production costs, 10–12 which put great constraints on the commercial development of OPVs.…”

Stable dinitrile end-capped closed-shell non-quinodimethane as a donor, an acceptor and an additive for organic solar cells

“…6,7 In the last 10 years, as immense efforts have been dedicated to the molecular design of non-fullerene acceptors (NFAs), the power conversion efficiencies (PCEs) of single-junction OSCs have made great progress. 8–18…”