Synthesis And Performance Analysis Of Organic Semiconductor Materials Based On Porphyrins And 1,4-Diketopyrrole [3,4-c]pyrroles Units

Organic semiconductor materials have used in a number of areas,such as organic solar cells（OSCs）,organic electrochemical transistors（OECTs）,Organic Light Emitting Diodes（OLEDs）and so on.In this paper,a series of porphyrin and diketopyrrole-pyrrole derivatives with great-π-conjugated rings structure were synthesized by using materials of pyrrole,thiophene and so on,which were used in OSCs and OECTs.We explore the effects of porphyrin and diketopyrrole-pyrrole derivatives to device performance of OSCs and OECTs.The porphyrin derivatives were used in OSCs,and the effect of porphyrin derivatives structure,linker group,end group and side group,to device performance were explored.The diketopyrrole-pyrrole derivatives were used in OECTs,and their device performance were improved by optimizing the main chain and side chain.The intermediates and target molecules were characterized by NMR,MADLI-TOF-mass and Fourier transform infrared spectroscopy（IR）.The photophysical and electrochemical properties of target molecules were studied using density functional theory（DFT）calculation,Ultraviolet-visible absorption spectroscopy（UV-Vis）and cyclic voltammetry（CV）.The atomic force microscopy（AFM）was used to analyze the morphology of the blend film of donor and recipient materials.The powder diffraction was used to analyze the of crystallization property of polymer.The thermal properties of target molecules were analyzed by thermodynamic analysis（TGA）and differential scanning calorimetry（DSC）.The detailed researches as following:（1）Four A-π-D-π-A of small molecule donors（Por-T,Por-TT,Por-DT and Por-BDT）were designed and synthesized.The linker group of these small molecule donors was modified with thiophene,thionothiophene,dithiophene and benzodithiophene respectively.The results shown that the photoelectric conversion efficiency of Por-BDT,whose linker was benzodithiophene,was highest among of these small molecule donors.Besides,after treating with solvent vapor,the electron mobility（μ_e）of Por-T,Por-TT,Por-DT and Por-BDT was 2.25×10^-4 cm²V^-1s^-1,1.48×10^-4 cm²V^-1s^-1,1.02×10^-4cm²V^-1s^-1 and 1.92×10^-4 cm²V^-1s^-1,and the OSCs device efficiency improved to 7.87%,6.64%,3.92%and 8.59%,respectively.（2）Three A-π-D-π-A of small molecule donors（DTTTPor-1,DTTTPor-2 and DTTTPor-3）were designed and synthesized.The end group of these small molecule donors were modified with 3-ethyl-rhodanine,2-（3-hexyl-4-oxothiazolidin-2-ylidene）malononitrile and 2-（3-oxo-2,3-dihydro-1H-inden-1-ylidene）malononitrile.The results shown that theμ_e of DTTTPor-1,DTTTPor-2,and DTTTPor-3 was 1.02×10^-4 cm²V^-1s^-1,2.13×10^-4 cm²V^-1s^-1 and 2.19×10^-4 cm²V^-1s^-1,and the ratio of holes and electrons mobility was 1.09,0.74 and 0.57,respectively.Besides,the OSCs device efficiency of DTTTPor-1 was highest（up to 8.91%）among these small molecule donors.（3）Five porphyrin-based small molecule donors（Por-1,Por-2,Por-3,Por-4 and Por-5）,which possessed different side group,were designed and synthesized.Theμ_e of Por-1,Por-2,Por-3,Por-4 and Por-5 was 1.57×10^-4 cm²V^-1s^-1,1.06×10^-4 cm²V^-1s^-1,1.07×10^-4 cm²V^-1s^-1,1.08×10^-4 cm²V^-1s^-1 and 3.70×10^-4 cm²V^-1s^-1.The results shown that theμ_e of Por-1,Por-2,Por-3 and Por-5 was higher an order magnitude than that Por-4.In here,the side group of porphyrins of Por-1,Por-2,Por-3 and Por-5 was replaced by alkyl-thionothiophene,and the side group of porphyrins of Por-4 was replaced by alkyl.What is more,the Por-1,whose side group was n-hexyl,possessed the highest OSCs device efficiency,which was up to 8.30%.（4）Three polymers（P1,P2 and P3）with different alkyl chain or backbone structure were designed and synthesized,and the results shown that theμ_e of P1,P2 and P3 was 9.5×10^-2 m²V^-1s^-1,8.7×10^-2 m²V^-1s^-1 and 4.4×10^-2 m²V^-1s^-1.The cyclic voltammetry results shown that when the Bis-EDOT was introduced into the backbone,the HOMO energy level decreases,the absorption spectrum widens and the band gap narrows.Besides,the OECTs based on P2,in which the Bis-EDOT introduced into the backbone and the triethylene glycol served as the side group,shown low voltage threshold,high transconductance,high switching current ratio and fast response.What is more,the measurement found that the drain current of OECTs based on P2 is almost not attenuated after the operation of 8 h continuous pulsed gate voltage switching,which shown that the P2 was a very promising material of OECTs device.（5）Four polymers（P4,P5,P6 and P7）with same DPP-bis EDOT backbone structure were designed and synthesized,whose ratio of hydrophilic and hydrophobic groups was different in the side group of DPP unit.The results shown that when the proportion of ethoxy side chain was increased,the performance of OECTs device was become better,including low voltage threshold and high switching current ratio.The OECTs based on P4,the ratio of ethoxy side chain up to 100%,shown the excellent device performance,whose voltage threshold was-0.139 V,transconductance was0.463 m S,switching current ratio was 2.85×10⁴,and the switching response time was2.9 us.