Tuning the Intermolecular Electrostatic Interaction toward High‐Efficiency and Low‐Cost Organic Solar Cells

Abstract

Organic solar cells (OSCs) have achieved much progress with rapidly increasing power conversion efficiencies (PCEs). It should be noted that the top-performance OSCs are generally consisted of active materials with complex chemical structures, resulting in high costs. Here, combining the material design and morphology control, high-efficiency OSCs are fabricated by a low-cost donor: acceptor blend. A completely non-fused electron acceptor named Tz is designed and synthesized via introducing thiazole units on both sides of a bithiophene core, which shows an outstanding PCE of 13.3% with a typical polythiophene donor. More importantly, optimization guidelines are presented to get excellent morphology for low-cost donor:acceptor systems. Three polythiophenes are selected, poly(3-hexylthiophene) and its two derivatives with electron-withdrawing substitutions (PDCBT and PDCBT-2F), as donors to fabricate the cell devices. The computational and experimental data reveal that decreasing the electrostatic interaction between polythiophene and Tz is the key to getting a suppressed miscibility and thus a high phase purity. This study provides insight into the molecular design and donor:acceptor matching requirements for high-efficiency and low-cost OSCs.

Peelable Microwave Absorption Coating with Reusable and Anticorrosion Merits

“…Meanwhile, the difference of electrostatic potential distribution calculated by density functional theory (DFT) (Figure 4i) would further promote the electrons' migration 56 to enhance the conductive loss, and the existence of positive and negative potentials as the active sites would be conducive to polarizations. 57 For the SL(C + P) specimen, the pure CNT without a well-designed impedance matching layer (PANI) is endowed with high conductivity due to the free electrons migrating through its surface according to the skin effect, which leads to a major electromagnetic wave reflection on the surface. Hence, the dielectric loss responses of SL(C + P) to the slight incident electromagnetic wave are weakened, showing the minor semicircles and lower slopes of the tail than that of SLCP20.…”

Strengthening the Hetero‐Molecular Interactions in Giant Dimeric Acceptors Enables Efficient Organic Solar Cells

“…In previous studies, introducing strong electron-deficit groups in the end-capped acceptor units or the central core, such as cyan group or halogen atoms, is an effective strategy to enhance molecular ESP value. [31][32][33][34][35] Besides, the smaller Flory-Huggins interaction parameter (closer surface energy) is related to the increased intermolecular interaction between donor and acceptor, and the surface energy of the acceptor is always larger than that of the donor. [36,37] Hence, aiming to strengthen the hetero-molecular interaction by increasing ESP value and reducing the surface energy of G-Dimer, a strong electronegative functional group with lower surface tension of the trifluoromethyl group was introduced into the quinoxaline core, and we further designed and synthesized another G-Dimer of Dimer-2CF, which shows a largely improved average ESP value of 5.51 Kcal mol −1 (Figure 1a,b).…”

Synthesis of Long‐Chain Oligomeric Donor and Acceptors via Direct Arylation for Organic Solar Cells†

“…[ 25‐28 ] By introducing conformation locks ( e.g ., F···H, S···N, O···S, and F···S non‐covalent intramolecular interactions), UFRAs can exhibit comparable geometries, stacking models, carrier mobilities, and thus device performances with FREAs. [ 29‐35 ]…”