Enhanced Optical And Electrical Performances Of Organic Field-effect Transistors Via Interfacial Modifications

Organic field-effect transistor?OFET?is a promising electronic device with substantial attention due to its lightweight,flexibility,large-scale yields,and low cost.In addition,spectral tunability and long photocarrier lifetime for organic active materials make it highly attractive for advanced optoelectronic device applications.For improving the OFET performance and lifetime,interfacial modification is also a key factor in addition to the selection of appropriate organic semiconductors and innovative device structure.This thesis firstly reviewed the research progress,application fields,research status and current challenges of OFETs in recent decades,and then introduced the basic structure,working principle,materials and preparation process,and performance parameters of OFET.Aiming at the low performance and poor stability,we focused on the improvement of OFET performance and stability by interfacial modifications.The main work is as follows:?1?The introduction of PVA and OTS at the carrier transfer interface(SiO₂/C₆₀)resulted in the fact that the deposited C₆₀ films on PVA/OTS successive-modified SiO₂ substrate were highly dense polycrystalline and uniform with larger crystalline grain and less grain boundary.On the other hand,a gap state assisted electron injection mechanism was proposed by inserting a BCP buffer layer at the charge injection interface(Al/C₆₀).The above studies showed that the interfacial modification enhanced the crystallinity of the C₆₀ thin film and reduced the electron injection barrier,which increased the carrier mobility and on-off current ratio,reduced the subthreshold slope,and significantly improved the photoresponsivity and external quantum efficiency of OFET.The maximum mobility and highest photoresponsivity of synergistic interfacial modifications device can reach up to 0.31 cm²V^-1s^-1 and 234 A/W at 50 V gate voltage,respectively,which are even higher than those of commercially available gallium nitride UV photodiodes?GUVA-S12SD?.Meanwhile,the interfacial modifications also improved the device's air stability.?2?We designed a high-performance broadband organic phototransistor based on C₆₀/AlClPc heterojunction.This elaborate design,with respect to the materials,interfaces and energy levels,led to a high-efficiency exciton-dissociation interface and complementary spectral absorption.And the corresponding photodetector obtained an ultrahigh photoresponsivity of 94.4 A/W,the highest detectivity ¹.5×10¹³ Jones combined with external quantum efficiency of 26066%,and the ability to measure high-frequency signals.These parameters are comparable or even superior to commercially available inorganic photodetectors.