Targeted Adjusting Molecular Arrangement in Organic Solar Cells via a Universal Solid Additive

Abstract

The incorporation of solid additive has been considered as an effective strategy for developing organic photovoltaics with multi-components, which is independent of dynamics, playing unique roles in morphology adjustment. However, their complex working mechanisms involving specific chemical structures are selective to material systems, hence limiting their university and flexibility in application. Herein, an inert small-molecular compound naphtho[1,2-c:5,6-c′] bis[1,2,5]thiadiazole (NT) is introduced into the bulk-heterojunction blend as the solid additive, which can function with various material systems and solvents, depending on its simple π-conjugated structure and S⋯N interaction for adjusting molecular alignment. It is interesting to note that the introduced NT can not only improve device performance, but also simplify complicated pre-or post-processing methods, reduce impact from batch-to-batch differences, construct sufficient energy transfer channel as well as improve device stability. The resulting devices based on PTzBI-dF:Y6-BO system show an impressive power conversion efficiency of 17.4% with obviously enhanced T 80 lifetime of >1200 h. These findings provide useful guidelines for exploring potential universal solid additives benefitting toward commercial application.

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

“…Reproduced with permission. [ 110 ] Copyright 2022, Wiley‐VCH. e) SEM image and the supposed illustration of PM6/BTP‐eC9 blend morphology.…”

“…introduced inert small molecule NT as an additive in the PTzBI‐dF:Y6‐BO system, which can modulate the molecular arrangement in the active layer through the S···N interaction and π‐conjugated structure of the benzothiadiazole unit, act as a compatibilizer during the drying process, and induce crystallization by working as a potential nucleation center ( Figure 10d). [ 110 ] Therefore, the incorporation of NT not only resulted in a PCE of 17.4% but also improved the stability of the device with a T 80 lifetime of more than 1200 h under illumination. Kang et al.…”

“…d) Schematic illustrations of the different molecular arrangements with liquid and solid additives. Reproduced with permission [110]. Copyright 2022, Wiley-VCH.…”

Observation of reversible light degradation in organic photovoltaics induced by long-persistent radicals

“…S1, ESI †). 27 For stability studies, we fabricated OSCs with an inverted device structure of ITO/ZnO NPs/PTzBI-dF:Y6-BO/MoO x /Ag. The active layers of PTzBI-dF:Y6-BO were thermally annealed at 110 1C for 10 min before evaporation for optimized device fabrication.…”

“…20,23 Degradation in opencircuit voltage (V OC ) can be observed when higher energetic disorder leads to broader density of states (DOS) or when the charge recombination process becomes more pronounced, resulting in a lower charge carrier density or higher non-radiative energy loss. 24 Despite achieving devices with improved stability through molecular design, 25,26 morphology adjustment [27][28][29][30][31] and interface engineering, 32,33 the specific roles played by light and heat in the degradation process of organic solar cells (OSCs), especially in high-performance NFA-based systems, still remain unclear. In general, light can be converted to heat through a non-radiative recombination process, and heat accumulation can act as a driving force for molecular motion, which facilitates the transition of metastable blend morphology to a stable state.…”