Studies On Performance And Sensing Property Of Bipolar Organic Thin Film Transistors Prepared By Blend

With the advent of new high performance,highly soluble organic semiconductor materials,solution-based methods is considered to be the most effective method for achieving large-area,low-cost,high-performance flexible printed electronics.Pure organic semiconductors have a single performance and narrow application range.In order to develop new properties of materials and satisfy various applications,the method of blending with insulators is widely used because of its easy operation and low cost.At present,the second-generation organic semiconductor materials represented by polythiophene are mainly used in the research of solution blend insulators.The phase behavior of the third generation of high-performance D-A conjugated polymers in the blending system is not yet clear,which limits the application of these materials.This paper studies the phase behavior of D-A type semiconductor PBIBDF-BT blended with different insulators,as well as the device performance and sensing characteristics.The main content and work are as follows:(1)The phase behaviors of DBI semiconductor PBIBDF-BT with different insulators and their effects on device performance were studied.The characterization results of atomic force microscopy show that blending with high molecular weight polystyrene(PS,Mn=140000 g/mol)produce ultra-thin semiconductor films.Porous semiconductor films were prepared by blending with low molecular weight polybutylene adipate(PBA,Mn=2000 g/mol).The device performance test results reveal that when the semiconductor concentration in the blend system with PS is below 2 mg/mL,the hole performance of the device increases with the increase of semiconductor concentration.In the blend system with PBA,the hole and electron properties of the device increase first and then decrease with increasing PBA content.(2)The effects of cyclic small molecule BNCAB on the performance and environmental stability of bipolar semiconductor PBIBDF-BT devices were studied.As the content of small molecule BNCAB increases,the electron mobility of the device first increases and then decreases,and the device switching ratio gradually increases.At a BNCAB content of 10 wt%,the device exhibits the highest electron mobility(0.12 cm2V-1s-1)and the largest switching ratio(106).Atomic force microscopy results showed that when the content of BNCAB was 10 wt%,the small molecule and the semiconductor phase separated to form a layered effect.Two means of UPS and GIXRD indicate the reason of enhancing N-type performance and environmental stability is the coverage of small molecule.(3)The sensing characteristics of the porous active layer OTFTs and the relationship between the pore size of active layer and the device sensing performance were studied.Porous active layer devices were prepared by the blending method,and the pore size of the active layer was analyzed by software.The results showed that the PBA content varied from 0 wt%to 50 wt%,and the active layer pore size increased from 0 nm to 154 run.Relative humidity sensing test results show that the larger the pore size of the porous active layer,the greater the response of the sensor to relative humidity,the faster the response.The porous structure allows gas molecules to diffuse into the charge transport layer more easily,resulting in OTFTs-type humidity sensors with high sensitivity(Ioff/Ion = 415)and fast response(Tres = 0.68 s).