A Vinylene‐Linker‐Based Polymer Acceptor Featuring a Coplanar and Rigid Molecular Conformation Enables High‐Performance All‐Polymer Solar Cells with Over 17% Efficiency

Abstract

State‐of‐art Y‐series polymer acceptors are typically based on a mono‐thiophene linker, which can cause some twisted molecular conformations and thus limit the performance of all‐polymer solar cells (all‐PSCs). Here, a high‐performance polymer acceptor based on vinylene linkers is reported, which leads to surprising changes in the polymers’ molecular conformations, optoelectronic properties, and enhanced photovoltaic performance. It is found that the polymer acceptors based on thiophene or bithiophene linkers (PY‐T‐γ and PY‐2T‐γ) display significant molecular twisting between end‐groups and linker units, while the vinylene‐based polymer (PY‐V‐γ) exhibits a more coplanar and rigid molecular conformation. As a result, PY‐V‐γ demonstrates a better conjugation and tighter interchain stacking, which results in higher mobility and a reduced energetic disorder. Furthermore, detailed morphology investigations reveal that the PY‐V‐γ‐based blend exhibits high domain purity and thus a better fill factor in its all‐PSCs. With these, a higher efficiency of 17.1% is achieved in PY‐V‐γ‐based all‐PSCs, which is the highest efficiency reported for binary all‐PSCs to date. This work demonstrates that the vinylene‐linker is a superior unit to build polymer acceptors with more coplanar and rigid chain conformation, which is beneficial for polymer aggregation and efficient all‐PSCs.

Sequential Processing Enables 17% All-Polymer Solar Cells via Non-Halogen Organic Solvent

“…The chemical structures of the polymers, the energy levels and device fabrication schematic are shown in Figure 1 , where different active layer deposition processes, blend-casting (BC) and sequential processing (SqP) are depicted in an abridged general view in Figure 1 c. The chemical structural formulas of PM6 and PY-V- γ are shown in Figure 1 a. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the materials are literature values [ 35 ]. As Figure 1 b shows, the energy level matching of each layer is favorable, and such a combination can maximize the efficiency and reduce the energy loss.…”

Computational chemistry-assisted design of a non-fullerene acceptor enables 17.4% efficiency in high-boiling-point solvent processed binary organic solar cells

“…Remarkably, the optimized BOEH-4Cl-based devices presented the best efficiency of 17.4%, which is one of the highest efficiencies for HBPS-processed binary OSCs. 39,42,43,46,51–53 In contrast, the V OC , J SC and FF were all reduced for the HBPS-processed L8-BO-based devices. It suggested that the morphology of BOEH-4Cl can be positively modulated by HBPS processing, demonstrating its great potential for mass production.…”

Blueshifting the Absorption of a Small‐Molecule Donor and Using it as the Third Component to Achieve High‐Efficiency Ternary Organic Solar Cells

“…[7][8][9][10][11][12][13][14][15][16] More importantly, OSCs provide many additional advantages that conventional inorganic solar cells do not have, such as solution processability, portability, and mechanical flexibility, which make OSCs more competitive among various generations of solar cell technologies. [17][18][19][20][21] Generally, there is a photoactive layer in OSCs with a bulk heterojunction (BHJ) structure, which contains an electron donor and an electron acceptor to perform the functions of photon harvesting, exciton dissociation, and charge transport. [22][23][24] However, the absorption of the two components is not able to cover the panchromatic solar spectrum because of the limited absorption range of classical organic photovoltaic materials.…”