The Preparation Of Carbon Quantum Dots Film And Electroluminescent Devices

As a quasi-zero-dimensional semiconductor nanomaterial,carbon quantum dot?CD?has shown the promising features of low toxicity,easy preparation,high fluorescence efficiency.It is considered to apply in thin-film solar cells,light emitting diodes,light catalysis,detectors,sensors,biological probes et al.In this disseration,the preparation conditions of carbon quantum dot film was carried out for electroluminescent devices application.The main results are as follows:?1?By using precursors of citric acid?CA?and 1-octadecylamine(C₁₈H₃₈N,ODA),we have synthesized carbon quantum dots sample in high-temperature liquidphase.In choice of solvents including chloroform and toluene,the solution-dispersion of CD and the film roughness are comparatively characterized.The conclusion indicated that the polarity of the solvent for carbon quantum dots solution is a key factor to the fluorocarbon dots film formation.The film roughness is related to ultrasonic duration of CD solution in which the prolonged time is required for smooth and continuous films.The layer by layer?LBL?assembly method of CD film was performed by alternate deposition of positive PDDA and modified CD from amphiphilic monoalkyl maleate.We also fabricated the electroluminescent devices from hybrid CD/PMMA film and amphiphilic polymers CD/PVP film.The turn-on voltage for two devices are 8V and 2.5V respectively and the hybrid CD/PVP film exhibits 4 times enhancement in luminescence intensity.?2?A electroluminescent devices with dual emission layer was fabricated with the structure of ITO/PEDOT:PSS/PVK/CD/Al.The device behavior is evaluated by introducing functional layer LiF and PMMA.With additional Li F layer,the device operating voltage can be reduced.The exciton recombination region is modulated at PVK layer under low voltage at interface of PVK and carbon quantum dots layer under the high electric field.The induction of the charge blocking layer PMMA is found to tune the device to warm white range by exciton recombination at carbon quantum dot layer..The CD concentration influence on EL spectra is characterized in which the device show a blue-shift and current increase with low concentration CD.