Linker Engineering of Dimerized Small Molecule Acceptors for Highly Efficient and Stable Organic Solar Cells

Abstract

High power conversion efficiency (PCE) and long-term stability are important requirements for commercialization of organic solar cells (OSCs). In this study, we demonstrate efficient (PCE = 18.60%) and stable (t 80% lifetime > 4000 h) OSCs by developing a series of dimerized smallmolecule acceptors (DSMAs). We prepared three different DSMAs (DYT, DYV, and DYTVT) by using different linkers (i.e., thiophene, vinylene, and thiophene− vinylene− thiophene), to connect their two Y-based building blocks. We find that the crystalline properties and glass transition temperature (T g ) of DSMAs can be systematically modulated by the linker selection. A DYV-based OSC achieves the highest PCE (18.60%) among the DSMA-based OSCs owing to the appropriate backbone rigidity of DYV, leading to an optimal blend morphology and high electron mobility. Importantly, the DYVbased OSC also demonstrates excellent operational stability under 1-sun illumination, i.e., a t 80% lifetime of 4005 h.

Conjugated polymers and small molecules containing the thiophene–vinylene–thiophene (TVT) unit for organic photovoltaic applications

“…TVT linker endowed L7 with high crystallinity, charge mobility, high T g , and low diffusion coefficients at 85 °C. Consequently, the devices delivered an impressive PCE of 17.60% and outstanding stability with a t 80% lifetime of 4005 h. 112 In summary, the SMs tended to exhibit hindered extensive aggregation and displayed effective p-p stacking, thereby the suitable domains with crystalline structures facilitated charge transport in the blend lms and yielded higher performance when TVT was used as the linker between two bulky units. The TVT linker also gives the target material a stronger absorption spectrum and higher charge mobility due to the prolonged conjugation of TVT groups.…”

“…TVT linker endowed L7 with high crystallinity, charge mobility, high T g , and low diffusion coefficients at 85 °C. Consequently, the devices delivered an impressive PCE of 17.60% and outstanding stability with a t 80% lifetime of 4005 h. 112…”

Modular‐Approach Synthesis of Giant Molecule Acceptors via Lewis‐Acid‐Catalyzed Knoevenagel Condensation for Stable Polymer Solar Cells

“…Figure 1b shows the synthetic routes to methylene-based A-link-A units, for which, both conjugated and flexible linkers were designed as previous studies indicates that linkers greatly affect the photophysical properties of GMAs. [26][27][28][29][30][31][32][33][34]38] B-DIC and L-n-DIC could be directly synthesized through the Suzuki coupling reaction by coupling L4-n (where n = 3, 4, 5) or L3 with IC-Br. However, the crude product of V-DIC, based on vinyl-based linker, is insoluble in common solvent (toluene, chloroform) due to a stiff aromatic structure, making its purification impossible.…”

Machine learning of atomic force microscopy images of organic solar cells

“…[1][2][3] Owing to recent advancements in high-performance p-type conjugated polymers and n-type nonfullerene acceptor molecules (NFA), [4][5][6] the power conversion efficiency (PCE) of OPVs has signicantly increased to nearly 20%. [7][8][9][10][11] High performance is achieved through efficient photoenergy conversion processes comprising photoabsorption, exciton diffusion, charge separation and charge transport with minimal loss. [12][13][14][15] One of the essential factors in facilitating these multi-physical phenomena is optimising the bulk heterojunction (BHJ) structure of a p/n-blended lm, which is fabricated through a solution process, including a p/n blend ratio, solvent, additive and annealing.…”