Study Of Sprayed Organic Solar Cells And Crosslinked Blue Light Emitting Diodes

In contrast to inorganic semiconductors,organic semiconductors possess many intriguing properties such as low-temperature processability,flexibility and diverse colours as well as cost-effective applications,which have broad application prospects.Organic solar cells（OSCs）directly convert solar energy into electricity,which is one of the most promising and effective technologies in green energy.Organic light-emitting diodes（OLEDs）are developing rapidly in the field of display and lighting and have great potential for development due to the advantages of quick response,high brightness and low energy consumption.As main applications of organic semiconductors,the research on OSCs and OLEDs is therefore of great importance.In this paper,sprayed OSCs and crosslinked OLEDs are studied in depth.1.For OSCs,the vertical and lateral micro/nanometer-scale structure in the active layer can largely determine the device performance.In this work,the surface and bulk domain sizes of the photoactive layer are successfully manipulated with a facile two-step spraying method,viz.an ultrathin active layer by high-pressure spraying is deliberately stacked on top of the thick active layer by ultrasonic spraying.The film morphology is effectively optimized with comprehensive study of optical and electrical characteristics,such as photon absorption,exciton dissociation efficiency and bimolecular recombination,etc.Moreover,synergistic effect of ultrasonic and high-pressure gas spraying can be used not only in the fullerene system but also in the non-fullerene system,demonstrating the remarkable universality through this synergy method.Fullerene OSCs based on PTB7:PC₇₁BM and non-fullerene OSCs based on PBDB-T:IT-M prepared by this novel method have achieved power conversion efficiencies of 6.48%and 8.06%respectively,which is the highest efficiency reported for ITO-free spraying organic solar cells up to date.This work provides an easy and reliable strategy to improve photovoltaic device performance in the industrial large-area spray-coating process.2.A new crosslinkable sky-blue polymer has been rationally designed and synthesized.The occurrence of the cross-linking reaction is certified from Raman absorption spectrum analyses.UV-vis absorption,photo-and electro-luminescence spectra studies indicate that this cross-linked emitting material has excellent thermal stability and solvent resistance.The device with the crosslinked emissive layer shows high luminous efficiency of 3.43 cd A^-1,low turn-on voltage of 4.3 V and maximum brightness of 7491 cd m^-2,which is the highest efficiency reported so far for blue light-emitting polymers based on crosslinked emissive layer.These results indicate that the introduction of a crosslinking group in the emissive layer material structure is a very promising strategy for the development of highly efficient and stable blue polymers used in multilayer solution-processed devices.