Delicate Morphology Control Triggers 14.7% Efficiency All‐Small‐Molecule Organic Solar Cells

Abstract

Morphology is a critical factor to determine the photovoltaic performance of organic solar cells (OSCs). However, delicately fine-tuning the morphology involving only small molecules is an extremely challenging task. Herein, we demonstrate a simple, generic, and effective concentration induced morphology manipulation approach to prompt both the state-of-the-art thin-film BTR-Cl:Y6 and thick-film BTR:PC 71 BM all-small-molecule (ASM) OSCs to a record level. The morphology is delicately controlled by subtly altering the prepared solution concentration but maintaining the identical active layer thickness. The remarkable performance enhancement achieved by this approach mainly results from the enhanced absorption, reduced trap-assistant recombination, increased crystallinity, and optimized phase-separated network. These findings demonstrate that concentration induced morphology manipulation strategy can further propel the reported bestperforming ASM OSCs to a brand-new level, and provide a promising way to precisely control the morphology towards high-performance ASM OSCs.

Understanding the Effect of End Group Halogenation in Tuning Miscibility and Morphology of High‐Performance Small Molecular Acceptors

“…Organic solar cells (OSCs) have great prospects for many industrial applications thanks to their flexibility, semitransparency, and light weight. [ 1–6 ] Nonfullerene small molecular acceptors (SMAs) [ 7–29 ] are the main driving force for the recent development of the field, with power conversion efficiencies (PCEs) over 17% reported by different teams. [ 30–43 ] SMAs have many attractive properties including their strong and tunable absorption, the easily adjustable energy levels and the enhanced chemical and device stability.…”

Reducing VOC loss via structure compatible and high lowest unoccupied molecular orbital nonfullerene acceptors for over 17%‐efficiency ternary organic photovoltaics

“…Hence, Y6 and its derivatives are extensively reported and used in recent research work. [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] For instance, other D-A copolymer donors, such as PTQ10, P2F-EHP, D16, W1, and D18, have been paired with Y6 to achieve excellent PCEs of 15% to 18%. [59][60][61][62][63] Besides, several research groups employed fullerene derivatives and Y6 to construct dual-acceptors ternary OPVs.…”

“…OSCs based on PM6: Y6 exhibited high electroluminescence quantum efficiency and low nonradiative recombination loss. Hence, Y6 and its derivatives are extensively reported and used in recent research work 43‐58 . For instance, other D‐A copolymer donors, such as PTQ10, P2F‐EHP, D16, W1, and D18, have been paired with Y6 to achieve excellent PCEs of 15% to 18% 59‐63 .…”

High‐Efficiency Ternary Organic Solar Cells Based on the Synergized Polymeric and Small‐Molecule Donors

“…[13,38,43,44] A chlorinated donor BTR-Cl shows relatively a lower-lying highest occupied molecular orbital (HOMO), compared with the pristine BTR, resulting in high PCEs of 14.7% and 15.3% for BTR-Cl:Y6 binary device and BTR-Cl:Y6:PC 71 BM ternary device, respectively. [45][46][47] Nevertheless, to simultaneously accomplish the morphological and optoelectronic tuning of BHJ OSCs, it requires the appropriate design of molecular components to fulfill the prerequisites of energetics, absorption, and miscibility to the original binary blends. Though challenging, it should be valuable to explore the new yet effective molecules that can address the critical trade-off between the photovoltage and photocurrent of OSCs.…”