Work

Ultra‐Thin Polyimide‐Embedded Carbon Nanotube‐Based Transparent Conductor and Its Application to Foldable Perovskite Solar Cells

Year: 2026

Type: article

Abstract: Ultra‐thin (~2.0 μm) carbon nanotube‐embedded polyimide (CNT–PI) transparent conducting substrates were fabricated by blending two complementary polyimide (PI) precursors, anhydrous dimethylacetamide (DMAc)‐based and N ‐methyl‐2‐pyrrolidone (NMP)‐based systems at an optimized ratio prior to imidization. The DMAc‐based PI, synthesized from 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride and 2,2′‐bis(trifluoromethyl)benzidine, provides optical transparency and color neutrality through its charge‐transfer complexes suppressing fluorinated architecture. In contrast, the NMP‐based PI, synthesized from pyromellitic dianhydride and 4,4′‐oxydianiline, contributes mechanical robustness via efficient chain packing. The resulting hybrid CNT–PI films exhibit transmittance of ~90% at 600 nm, Young's modulus of ~ 5 MPa, glass‐transition temperature ( T g ) of 264.5 °C, and near‐complete color neutrality (Δ b * < 2 and Δ L * < 3). When implemented in foldable perovskite solar cells (PSCs), the ultra‐thin CNT–PI substrates enabled a power conversion efficiency (PCE) of 18.72% with exceptional mechanical durability, retaining 98.85% of its initial PCE after 10 000 folding cycles at a bending radius of 0.5 mm. The achieved efficiency represents the highest reported value among foldable PSCs utilizing CNT‐based transparent electrodes, while the ultra‐thin CNT–PI substrate exhibits a state‐of‐the‐art thickness among reported PI‐based flexible transparent conductor/substrate architectures.

Source: Small Structures

DOI: 10.1002/sstr.70585