Achieving Efficient Ternary Organic Solar Cells Using Structurally Similar Non‐Fullerene Acceptors with Varying Flanking Side Chains

Abstract

In this work, the properties and performance of three structurally similar non‐fullerene acceptors (named BTP‐Ph, BTP‐Th, and BTP‐C11) possessing different side chains on the β‐positions of the thienothiophene units of the Y6 molecule are systematically studied. The steric and electronic effects of these side chains on the blend morphology and device performance based on the PTQ10 donor polymer are investigated. It is found that the thiophene and benzene units on the side chains introduce more steric hindrance and thus slightly reduce the crystallinity of the molecule. However, an interesting matching trend with the PTQ10 donor that appears to better match with the less crystalline molecules is observed. Overall, PTQ10:BTP‐Ph delivers the highest performance of 17.1% due to the suitable phase separation among three blends. Next, a ternary strategy is explored by incorporating BTP‐Th/BTP‐C11 with better molecular packing into PTQ10:BTP‐Ph, which successfully extends photon response, enhances charge transport, and suppresses charge recombination compared with the binary blend. Due to these synergistic effects, the ternary device based on PTQ10:BTP‐Ph:BTP‐Th achieves an outstanding power conversion efficiency of 17.6% with a fill factor of 78.8%, which is the highest value of PTQ10‐based devices to date.

Alkyl‐Chain Branching of Non‐Fullerene Acceptors Flanking Conjugated Side Groups toward Highly Efficient Organic Solar Cells

“…But one should also expect the looser intermolecular packing and thus decreased charge mobility of the materials, which may in turn result in the trade-off between the short-circuit current density (J SC ) and fill factor (FF) of the resulting devices. [59] Among considerable efforts devoted to side-chain engineering of the A′-DAD-A′-type NFAs, branched alkyl chains are indispensable to be attached to the pyrrole rings at the inner positions of the central core, as they are vital to imparting good solubility and reducing domain sizes of NFAs. [60][61][62][63][64][65] In contrast, linear chains prevail in the outer side-chain design while branched chains are rarely adopted.…”

Exploring the Charge Dynamics and Energy Loss in Ternary Organic Solar Cells with a Fill Factor Exceeding 80%

“…[20] The crystalline silicon cells have very high FF over 81%, and the perovskite solar cells possess an impressive FF in the range of 79%-82%. [21] Unfortunately, most of the ternary OSCs suffer from relatively low FF (generally below 78%), [22][23][24][25][26][27][28] seriously limiting the device's performance. The low FF originates from poor charge transport and severe recombination in cells.…”

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

“…[8][9][10][11][12][13][14][15][16][17][18] Different from the binary OSCs, the ternary OSCs appear to an available strategy to extend light absorption, facilitate exciton dissociation and optimize the morphology, lending to the improvement of photovoltaic performances. [19][20][21][22][23][24][25][26][27] Cascade energy alignment could be achieved by introducing third component with suitable energy levels, which is beneficial to suppress charge recombination. 28,29 Another significant function of third component is to improve the compatibility and miscibility with the binary blend film.…”