Batch-Reproducible and Thickness-Insensitive Mesopolymer Zwitterion Interlayers for Organic Solar Cells

Abstract

Zwitterionic polymers or small molecules are a class of widely used interlayer materials in organic solar cells (OSCs). It is challenging to develop such materials that combine good film-forming property, high batch-to-batch reproducibility, and broad thickness processing window in device applications. Herein, we designed and synthesized two self-doped conjugated mesopolymer zwitterions (CMZs), namely, MT 2 PDIMz and MT 2 PDINz (PDI = perylenediimide, M = mesopolymer, T 2 = dithiophene, Mz = imidazolium zwitterion, Nz = ammonium zwitterion). Both show good processability and effectively reduce the work function of metal electrodes. The substitution of imidazolium cations with ammonium cations on the side-chains can further modulate the solution assembly and self-doping effect of CMZs, enabling improved interfacial compatibility with active layers and higher electron mobility in MT 2 PDIMz. The versatility of CMZs interlayers for OSCs is confirmed with several binary and ternary active layers, affording efficiencies up to 19.01%. Notably, over 98% of the optimal efficiency is maintained as the thickness of the interlayers increases to 40 nm with good reproducibility.

Reexamining the Role of Solution-Cast Ferroelectric Polymer Interlayer toward Enhanced Efficiency and Stability in Conventional Organic Solar Cells

“…Additionally, the device covered with a P(VDF-TrFE) film obtains a charge extraction time of 110 ns, which is shorter than those of the reference device (124 ns) and the DMF-rinsed device (121 ns) (Figure S6d). These results imply that the DMF-cast P(VDF-TrFE) interlayer could suppress charge recombination and improve charge extraction, 41 accounting for the enhancement of FF.…”

Asymmetric Π‐Bridge Engineering Enables High‐Permittivity Benzo[1,2‐B:4,5‐b′]Difuran‐Conjugated Polymer for Efficient Organic Solar Cells

“…The derived μ h and electron mobility (μ e ) of PBDF-TF-BTz:Y6 devices are 2.26 × 10 −4 and 2.48 × 10 −4 cm 2 V −1 s −1 , respectively, featuring a small μ e /μ h ratio of 1.09 (Figure 5b and Figure S36, Supporting Information). [44] In contrast, the μ e /μ h are 2.20 × 10 −4 /1.84 × 10 −4 cm 2 V −1 s −1 and 2.19 × 10 −4 /0.94 × 10 −4 cm 2 V −1 s −1 for PBDF-dT-BTz:Y6 and PBDF-dF-BTz:Y6 devices, respectively, featuring large μ e /μ h ratio of 1.20 and 2.33. Accordingly, the slower and less balanced charge mobility of PBDF-dT-BTz:Y6 and PBDF-dF-BTz:Y6 devices contribute to their inferior FF versus that of PBDF-TF-BTz:Y6 devices.…”

Cost-Effective Cathode Interlayer Material for Scalable Organic Photovoltaic Cells

“…For OPV cells, cathode interlayer (CIL) materials play a critical role in the electron transport and extraction processes. , However, the quantity of material used in the laboratory-scale OPV cell fabrication, typically in the milligram range, is far from sufficient when transitioning to R2R printing, where the materials are required on a scale of 10–100 g for initial processing condition optimization (Figure a). Furthermore, materials in significantly larger quantities are required for full-scale industrial production, and the variation from batch to batch must be eliminated. , Consequently, the simple synthesis and relatively low cost of materials becomes crucial. Additionally, the rate at which CILs are printed in the R2R process remains a significant concern.…”