Near-infrared double-cable conjugated polymers based on alkyl linkers with tunable length for single-component organic solar cells

The photovoltaic properties of double-cable conjugated polymers are significantly influenced by the length of the alkyl linkers that connect donor backbones and acceptor side units. In this study, a series of 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile(IC)-based double-cable polymers with alkyl linkers ranging from C_8H_(16)to C_(16)H_(32)(Px, x = 8, 10, 12, 14, 16) were synthesized for single-component organic solar cells(SCOSCs). Among these, the linker length x = 12(P12) is found to optimize the power conversion efficiencies(PCEs) in SCOSCs. Specifically, PCEs increase from P8 to P12 and then decline from P12to P16. Detailed investigations of optical absorption, charge transport, and morphology provide insights into the underlying factors contributing to these PCE variations. The findings indicate that the exceptional photovoltaic properties observed in P12 can be attributed to three key factors: A delicate balance between enhanced charge separation facilitated by the increased spacer length and reduced crystallinity resulting from longer spacers, higher charge mobilities, and well-balanced hole/electron transport characteristics. This study highlights the critical role of linker length in determining the photovoltaic properties of double-cable conjugated polymer-based SCOSCs and offers valuable guidance for the design of novel double-cable conjugated polymers.

Low temperature,non-halogen solvent processed single-component organic solar cells with 10%efficiency

A double-cable conjugated polymer DCPIC-BO is designed via introducing a long-branched alkyl chains 2-buthyloctyl into the acceptor side unit.Compared with the double-cable polymer(DCPIC-EH)with the 2-ethylhexyl alkyl chains,the solubility of the DCPIC-BO in non-halogen solvents is substantially improved.Therefore,a power conversion efficiency(PCE)of 9.77%can be obtained by the devices processed from o-xylene at 40℃,while the DCPIC-EH cannot be processed due to its poor solubility under this condition.Moreover,PCEs of 10.10%for small-area(0.04 cm^(2))devices and nearly 9%for devices with an area of 1 cm^(2) are achieved using a non-halogenated solid additive in o-xylene,realizing the"absolutely halogen-free"OSC fabrication.

Photo-responsive liquid crystalline vitrimer containing oligoanilines

Liquid crystalline vitimers （LC-vitrimers） can be easily processed into complex three-dimensional configurations. In this paper, we present a photo-responsive LC-vitrimer by simply introducing a photo- thermal agent aniline trimer into the LC-vitrimer system. As aniline trimer acts as a curing agent, it can be homogeneously dispersed in the material, avoiding aggregation which commonly happens to nano- fillers. As a result, the resultant polymer not only can perform three light-controlled functions （welding, healing and shape memory）, but also can be prepared into aligned monodomain LC actuators with strains of about 40%-45%.

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

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.