Light-Induced Conductivity in a Solution-Processed Film of Polydiacetylene and Perylene Diimide Hao Jiang, †,§ Guy Hershtig, ‡,§ Shachar Richter, ‡ and Raz Jelinek* ,† † Department of Chemistry, Ilse Katz Institute for Nanotechnology, Ben Gurion University of the Negev, Beer Sheva 84105, Israel ‡ Department of Materials Science and Engineering, Faculty of Engineering and University Center for Nano Science and Nanotechnology, Tel Aviv University, Tel-Aviv 69978, Israel *S Supporting Information ABSTRACT: We prepared a solution-processed film comprising a drop-casted mixture of melamine-diacetylene and perylene bis(dicarboximide) (PDI). We show that the diacetylene monomers adopt distinct crystalline organization in the presence of the PDI residues. Importantly, the drop-casted diacetylene/PDI film exhibits ultraviolet light- induced conductivity, ascribed to effective transport of charge carriers in the conjugated polymerized network. P olydiacetylenes (PDAs) are a family of conjugated polymers exhibiting remarkable photophysical properties, particularly unique visible and fluorescence light absorbance. 1−3 Because PDA is well-known as a quasi-one-dimensional (1D) π-conjugated polymer, specific charge carrier transport is expected due to the 1D electronic state. 4,5 Previous studies have shown, for example, that vacuum-deposited PDA films could function as p-type semiconductor components in an OFET. 6−8 However, PDA crystals are nearly complete insulators (exhibiting electrical conductivity on the order of σ ≈ 10 −12 S/cm), making their use in electronic applications rare. 9 Here, we report fabrication of a solution-processed film exhibiting light-induced conductivity from a mixture of melamine-displaying diacetylene and perylene bis- (dicarboximide) (PDI), a widely studied constituent of organic electronic devices. 10−12 The binary film featured distinct structural and morphological properties, reflecting segregated albeit intertwined domains of diacetylene and PDI, likely induced through hydrogen binding between PDI and the melamine units. Notably, we found that, following polymer- ization, the conjugated network of PDA played a significant role in enabling charge transport. The simple assembly process and interesting optical/electronic properties of the diacetylene- melamine/PDI drop-casted films could open new avenues for the use of PDA systems in optoelectronic devices. Figure 1 depicts the experimental scheme. The tricosadyi- noic-melamine (TrMel) monomer (Figure 1A) was prepared through substitution of the carboxylic acid head group of the commercially available monomer (10,12-tricosadiynoic acid) through a simple synthesis process. 13 Nonchemically function- alized PDI (Figure 1A) is commercially available and has been a common starting material in synthesis of numerous n-type organic semiconductors. The photoinduced conductive device was fabricated through dissolving a mixture of TrMel and PDI (2:1 mol ratio) in an organic solvent [1,2-dichlorobenzene (DCB)] and drop-casting the solution between two electrodes (while several organic solvents were examined, we found that DCB generated films with the most pronounced optoelectronic properties, as shown in Figure 1B). Subsequent ultraviolet (UV) irradiation (at 254 nm) of the dried film (after slow Received: March 27, 2016 Accepted: April 18, 2016 Figure 1. Solution-processed photoconductor from melamine- diacetylene and PDI. (A) Chemical structures of TrMel and unsubstituted PDI. (B) Photoconductor formed upon drop-casting TrMel and PDI film between the two electrodes. Letter pubs.acs.org/JPCL © XXXX American Chemical Society 1628 DOI: 10.1021/acs.jpclett.6b00690 J. Phys. Chem. Lett. 2016, 7, 1628−1631