Mechanical-robust and recyclable polyimide substrates coordinated with cyclic Ti-oxo cluster for flexible organic solar cells

Abstract

With the rapid development of flexible optoelectronic devices, recyclability is highly desirable for alleviating resource waste and environmental pollution, but remains challenging. Here, a fully closed-loop recyclable crosslinked polyimide (RCPI) was fabricated via carboxyl ligand exchange between the CPI with pendent carboxyl groups and the cyclic Ti-oxo cluster (CTOC) with labile carboxyl ligands, which could be reconverted into reprocessable CPI and CTOC solution by pivalic acid. The RCPI-based embedded AgNWs@RCPI electrode shows comparable high conductivity, transparency and low roughness with ITO (indium tin oxide)/glass electrode, and meanwhile outstanding mechanical robustness. The related flexible organic solar cells (FOSCs) provided a high efficiency of 14.78% and maintained ~97% of the initial efficiency after 5000 bending cycles at a small bending radius of 1 mm. Moreover, the recyclability of the RCPI still retains after being manufactured into the FOSCs. This work provides a promising strategy for recyclable flexible optoelectronic devices.