Geometry design of tethered small-molecule acceptor enables highly stable and efficient polymer solar cells

Abstract

With the power conversion efficiency of binary polymer solar cells dramatically improved, the thermal stability of the small-molecule acceptors raised the main concerns on the device operating stability. Here, to address this issue, thiophene-dicarboxylate spacer tethered small-molecule acceptors are designed, and their molecular geometries are further regulated via the thiophene-core isomerism engineering, affording dimeric TDY-α with a 2, 5-substitution and TDY-β with 3, 4-substitution on the core. It shows that TDY-α processes a higher glass transition temperature, better crystallinity relative to its individual small-molecule acceptor segment and isomeric counterpart of TDY-β, and a more stable morphology with the polymer donor. As a result, the TDY-α based device delivers a higher device efficiency of 18.1%, and most important, achieves an extrapolated lifetime of about 35000 hours that retaining 80% of their initial efficiency. Our result suggests that with proper geometry design, the tethered small-molecule acceptors can achieve both high device efficiency and operating stability.

Powering the Future: A Critical Review of Research Progress in Enhancing Stability of High‐Efficiency Organic Solar Cells

“…Bai et al employed a thiophene-dicarboxylate spacer to tether two SMAs. [82] The novel dimeric, TDY-𝛼, showed a more hypo-miscible system compared to the PM6:Y6 system, which suppressed the diffusion in the blend. As a result, TDY-𝛼based devices reached a high PCE of 18.1% and enhanced thermal and operational stability, which achieved an extrapolated T 80 lifetime of about 35 000 h. Overall, these findings suggest that the oligomerization of NF-SMAs is a promising approach to enhance the device performance and stability of OSCs, indicating the potential to improve the efficiency and lifetime of future solar cells.…”

Regulating the Sequence Structure of Conjugated Block Copolymers Enables Large‐Area Single‐Component Organic Solar Cells with High Efficiency and Stability

“…Even worse, the quasi‐equilibrium morphology of the photoactive mixture is usually unstable after a long period of light or thermal aging. For example, the evolution of the blend morphology from a kinetic trap state to a thermodynamically stable state, such as aggregation and donor/acceptor interface retreat, always produces large‐scale isolated domains and phase separation, resulting in serious efficiency and life degradation of OSCs [9–10] …”

Ductile Oligomeric Acceptor‐Modified Flexible Organic Solar Cells Show Excellent Mechanical Robustness and Near 18% Efficiency

“…[22][23][24] In addition, oligomer acceptors exhibit significantly higher glass transition temperatures (T g ) and reduced molecular diffusion kinetics, resulting in a stable active layer morphology. [25][26][27][28] Consequently, the resulting OSCs showed excellent photo and thermal stability. Huang et al recently reported that, by synthesizing oligomeric acceptors with different degrees of polymerization, the OSCs showed PCEs exceeding 15% and an extrapolated T 80 lifetime exceeding 25 000 h. [29] Currently, studies on oligomer acceptors have focused on improving the photo/thermal stability of OSCs, but their application in P D :SMA-based flexible OSCs for improved mechanical properties has never been reported.…”