Broadband-Solubility Diketopyrrolopyrrole Derivative with Both Polar Cyano and Nonpolar Alkyl Groups for Stable Organic Photosensors and Diffusion-Processed Organic Solar Cells

摘要

A small-molecular diketopyrrolopyrrole (DPP) derivative with cyano groups, (2E, 2'E)- diethyl-3,3'-((5,5'-(2,5-bis(2-ethylhexyl)3,6- dioxo- 2,3,5,6- tetrahydropyrrolo3,4-c pyrrole-1,4-diyl) bis(thiophene- 5,2- diyl)) bis(4,1- phenylene)) bis (2- cyanoacrylate) (EHTPPD-ECPA), was synthesized via Suzuki-coupling reaction. The synthesized EHTPPD-ECPA exhibited a broadband solubility in both polar and nonpolar solvents due to the presence of both polar (cyano) and nonpolar (alkyl) groups. A bright pink photoluminescence (PL) was measured from EHTPPD-ECPA solutions, whereas almost no PL was observed from the EHTPPD-ECPA films because of high intermolecular stacking (band gap=1.7 eV). EHTPPD-ECPA was found to act as an electrondonating component in all-small-molecular bulk heterojunction layers for organic photosensors (photodetectors), while it played a critical role in improving the efficiency of diffusion-processed polymer/fullerene solar cells with the mixed electron-donating layers.