Synthesis And Properties Of New Coumarin Sensitized Dyes

Five new coumarin dyes have been designed and synthesized assensitizers for the application in the dye-sensitized nanocrystalline solarcell （DSSC）． The structures of the dyes have been characterized by massspectra （MS） and proton nuclear magnetic resonance （1H NMR）technology.Coumarin derivatives2-cyano-3-（5-（2-oxo-2H-chromen-3-yl） thio-phen-2-yl）acrylic acid were synthesized starting from salicylaldehyde and2-thiopheneacetonitrile within three steps. The effect of several factors inthe first synthesis step, such as catalyst, ratio of raw materials, amount ofsolvent and reaction time was investigated. The process parameters wereoptimized and the optimal yields were obtained in the reaction ofsalicylaldehyde with2-thiopheneacetonitrile （1.2equiv） under the catalysisof piperidine in refluxing DMF（30mL） for6h.The fluorescence spectra of2-cyano-3-（5-（2-oxo-2H-chromen-3-yl）thiophen-2-yl）acrylic acid were investigated, showing that2-cyano-3-（5-（7-（diethylamino）-2-oxo-2H-chromen-3-yl）thiophen-2-yl）acrylic acid hadgood fluorescence performance and was fluorescent in solution emittingorange yellow light （510nm）. Three typical fluorescence peaks are foundin its three-dimensional fluorescence spectra.2-cyano-3-（5-（2-oxo-2H-chromen-3-yl） thiophen-2-yl） acrylic acidwere used in DSSC. Under simulated AM1.5(658mWcm^-2)，2-cyano-3- （5-（7-（diethylamino）-2-oxo-2H-chromen-3-yl）thiophen-2-yl）acrylic acidhad good solar energy-to-electricity conversion efficiency （η） of2.02%,open-circuit voltage （VOC） of0.582V, short-circuit current density （JSC） of3.44mA/cm², fill factor （FF） of0.67.