The Fabrication And Properties Analysis Of Phthalocyanine Series Organic Photoelectric Transistor

Organic electronic devices has the advantages of simple preparation process,low cost,can be made in large mass,can be compatible with flexible substrates,can fully meet the need of industry of the low electronic products.It has been applied in many fields successfully.The phthalocyanine series semiconductor materials have good photosensitive properties.In this paper,we select three kinds of the phthalocyanine organic materials?MPc?,which are phthalocyanine zinc?ZnPc?,lead phthalocyanine?PbPc?and copper phthalocyanine?CuPc?,and use them as the active layer.By using multi-function coating system,we prepared organic thin film transistors with vertical structure through vacuum deposition and magnetron sputtering process.The transistor structure is sandwich structure of indium tin oxide?ITO?/MPc/aluminum?Al?/MPc/copper?Cu?.There forms Schottky contact between Al and MPc,and ohmic contact between Cu/ITO and MPc.The preparation process is to deposite ITO,phthalocyanine organic materials,Al,copper phthalocyanine organic material and Cu on ordinary glass substrate,respectively.First of all,we test and analysis the schottky contact properties between organic film and Al base thin film.Then we test the output characteristics of the device in dark.The results show that the working driving is low,and the output current is high.It presents typical unsaturated current-voltage characteristics.When V_ec=3V,V_b=0V,the output current of the device preparated by three kinds of materials is?ZnPc?I_ec=5.9×10^-5A;?PbPc?I_ec=5.7×10^-5A;?CuPc?I_ec=6.6×10^-6A,respectively.According to the absorption spectrum of organic semiconductor material,by use the light in absorption peak?three kinds of materials is 618nm,800nm,and 625nm,respectively?to illuminate the corresponding devices,we test and analysis the photoelectric characteristics of devices.When selecting V_ec=3V,we analysis current magnification of the device in light and in dark.The current amplification ratio of ZnPc device under the condition of618 nm light changes from 1.25 to 1.33;The current amplification ratio of PbPc device under the condition of 800nm light is from 2.91-3.34.And the current amplification ratio of CuPc device under 625nm light is from 1.91 to 2.64.The photocurrent magnification of Phthalocyanine lead is bigger than the other two materials.In addition,through the transfer characteristic curve,we can obtain output current decreaces with the increasing base bias voltage.Finally,we use the CuPc device irradiated by 700nm wavelength light which is second crest as an example.Analyze the photosensitive mechanism of organic transistors.By calculating we obtain that the schottky barrier height of base area decreased 10meV after light,whicn makes the number of carriers injecting into the base area and then flowing to collector area bigger.Such formed the photosensitive current,which makes the output current increase.