Fused‐Ring Nonfullerene Acceptor Forming Interpenetrating J‐Architecture for Fullerene‐Free Polymer Solar Cells

Abstract

An interesting and important question emerges with the rapid advances of the highly efficient fused‐ring nonfullerene acceptors; that is, how the acceptor molecules form aggregates in its blended film with a donor polymer/small molecule so as to offer highly efficient exciton diffusion and electron transport? To answer this question, a new acceptor molecule, 3,9‐bis(5‐methylene‐4‐one‐6‐(1,1‐dicyanomethylene)‐cyclopenta[c]thiophen‐2,8‐dimethyl)‐5,5,11,11‐tetrakis(4‐n‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene (ITCT‐DM), is designed and synthesized herein and its unique interpenetrating J‐architecture is presented in which the acceptor molecules form compacted and displaced ππ‐stacks with the distances of 3.1−4.2 Ǻ. Again the crystal structure data are correlated with the grazing‐incidence X‐ray diffraction (GIXRD) data of the pure acceptor and its polymer:acceptor blended films, which gives a clearer picture about the origins of the acceptor's GIXRD signals in both the pure and its blended films. Again, these results unveil the key roles of the uses of 1,8‐diiodooctane (DIO) and thermal annealing treatment in optimizing the acceptor phase morphologies in the donor:acceptor blended film, and the combination of the thermal annealing and DIO treatment leads to obtain higher crystallinity for both the donor and acceptor phases, more compacted packing, and finer morphologies. A power conversion efficiency of 10.5% is obtained.

Ternary Blended Fullerene‐Free Polymer Solar Cells with 16.5% Efficiency Enabled with a Higher‐LUMO‐Level Acceptor to Improve Film Morphology

“…For the PM6:IT‐4F system, the face‐on oriented π–π stacking signal appears around 1.78 Å −1 ( d ≈ 3.53 Å). The peak around 1.35 Å −1 ( d ≈ 0.46 Å) could be due to the packing ordering of the perpendicular side chains of IT‐4F, as observed previously by us from the ITCT‐DM molecule . Upon the mixing with 0.2 IDIC, the π–π stacking scattering signal is seen around 1.77 Å −1 ( d ≈ 3.55 Å), featuring the addition of the (010) signals of the IT4F binary and the IDIC binary.…”

“…The peak around 1.35 Å −1 (d ≈ 0.46 Å) could be due to the packing ordering of the perpendicular side chains of IT-4F, as observed previously by us from the ITCT-DM molecule. [53] Upon the mixing with 0.2 IDIC, the π-π stacking scattering signal is seen around 1.77 Å −1 (d ≈ 3.55 Å), featuring the addition of the (010) signals of the IT4F binary and the IDIC binary. The CCL reflecting the crystalline size of the π-π stacking is estimated to be 3.86 nm for both the IT-4F binary blend and its ternary blend with the addition of 0.2 IDIC.…”

High‐Efficiency As‐Cast Organic Solar Cells Based on Acceptors with Steric Hindrance Induced Planar Terminal Group

“…[15,[26][27][28] So, the molecular conformation of the terminal region would directly influence the charge transport and the final photovoltaic performances. [15,[26][27][28] So, the molecular conformation of the terminal region would directly influence the charge transport and the final photovoltaic performances.…”

“…The π-π stacking of terminal moieties is now recognized to be the main charge transport channel for A-D-A type FREAs. [15,[26][27][28] So, the molecular conformation of the terminal region would directly influence the charge transport and the final photovoltaic performances. In this contribution, A-π-D-π-A type FREAs IDTCN-O, IDTCN-C, and IDTCN-S were designed based on the same molecular skeleton of IDTT2F with hexyl, hexyloxy, and hexylthio side chain, respectively, incorporated at the outer site of the thiophene bridge to systematically investigate the influence of side chain type on the photo voltaic performance.…”

Fused‐Ring Core Engineering for Small Molecule Acceptors Enable High‐Performance Nonfullerene Polymer Solar Cells

“…To enhance spectral response, several methods have been performed to modify the IDT-based acceptors, such as increasing the conjugation lengths, [11,22,33,34] introducing electron-donating groups in the D units, [24,26,28,35] and using strong electron-withdrawing atoms in the A groups. [16,23,25,36] Accordingly, several narrow-bandgap (NBG) fused-ring nonfullerene acceptors (NFAs), such as BTOIC, [12] IHIC, [37] 4TIC, [38] F8IC, [31] IEICO, [24] ATT-2, [39] BT-CIC, [40] DTPCIC, [41] COi8DFIC, [42] and R12-4Cl, [43] were successfully developed. Although these acceptors presented satisfying J SC , nonideal open-circuit voltage (V OC ) and fill factor (FF) limit the Small molecule acceptors (SMAs) for polymer solar cells (PSCs) have become a hot topic due to the resulting breakthrough of power conversion efficiency (PCE).…”