Research On Organic Thin Film Transistors

In recent decades, organic semiconductor materials has been received great attention.Inthis context, the research of organic thin film transistors (OTFTs) also has been started. Withits potential advantages solution-processed OTFTs has attracted considerable attention.Organic semiconductor materials play the main role in carrier transport, the intrinsic andinterface properties of semiconductor materials determines the nature of carrier transportspeed and the performance of OTFTs either.Poly (3-hexyl-thiophene)(P3HT) is a semiconductor polymer with excellentperformance and it usually used as the active layer of OTFTs. As for the important electrodematerial we used Ag electrode here. To compensate for the gap between the metal workfunction, the modification of PEDOT (3,4-ethylnedioxy thiophene) between Ag electrode andP3HT play a role to solve the problem about the work function mismatch. Rubrene as theactive layer materials have been used in the manufacture of OTFTs. The main contentsinclude:(1) Annealing temperature of P3HT has remarkable effects on its performance. By comparingfour selected samples, conductivity decreases with the increase of annealing temperatureand it achieves the best performance in the373K0.092A/cm2of current per unit area.Itpresents heat treatment has the significant influence on molecular arrangement andstructer of P3HT. Excess temperature will damage the microcrystalline structure ofP3HT,and lead the decrease performance deterioration of the conductivity(2) Test the resistor of P3HTwhich is made in spin-coated speed. The test results show thatthe best spin-coated speed is2000r/min.In this speed, get the best annealing temperature is413K for PEDOT through researching the change of resistor of PEDOT in differenttemperatures..(3) Interface modification of PEDOT significantly improves the unmatched work function ofAg and P3HT,and experiment results are identical with theoretical value. Injectionproperties of sample are now1.15~1.30times of original ones. The same sample achievesthe best performance in the373K (0.106A/cm2of current per unit area).(4) Experiment analyses the influence of P3HT density on OTFT. OTFT presents the bestperformance, which has higher field effect, higher carrier mobility and on/off currentratio, and lower threshold voltage when P3HT is15mg/ml.Meanwhile,AFM image alsoillustrates feature of P3HT in15mg/ml is the best, and surface roughness is minimum...