Design, Synthesis And Field Effect Properties Of Naphthalene/perylene-derived Imide Organic Semiconductor Material

N-type and ambipolar organic transistor have been widely concerned because of their important roles in complementary logic circuits.However,compared with progress of p-type organic transistors,the development of n-type and ambipolar organic transistors in terms of charge carrier mobility,and the type and amount of organic semiconductors is largely lagged behind.It is crucial to explore new type of organic semiconductors for n-type and anbipolar organic transistors.Compared with conjugated polymers,organic small molecules are not only simple to synthesize and easy to purify,but also have good repeatability.They are considered to be more potential semiconductor materials for printed electronics.The main research contents of this article are to modify the NDTI/DTCDI building blocks,expected to obtain high-performance air-stable,solution-processed n-type or ambipolar organic semiconductors for OFETs.The main research contents are as follows:1.The NDTI-based small molecules were desigened and synthesized,named NDTI-BTE,NDTI-BPE,NDTI-B2Pd E,NDTI-B4Pd E.The introduction of the arylacetylene groups at the thiopheneα-positions of NDTI endowed these molecules sufciently low-lying LUMO energy levels from–4.12 to–4.24 e V.Under ambient atmosphere,the solution-processed bottom-gate top-contact（BGTC）transistors based on thin-flms of these NDTIs exhibit n-type transport,among which NDTI-BTE has the best performance with the maximum electron mobilities of 0.049 cm² V-¹ s-¹.2.Two NDTI-based isomeric triads（NDTI-B2Az and NDTI-B6Az）were designed and synthesized,in which two azulene units were connected with NDTI at the2-position of the azulene ring in NDTI-B2Az,whereas two azulene units were incorporated with NDTI at the 6-position of the azulene ring in NDTI-B6Az.The HOMO orbital distribution of the traids is regulated by changing the connection position of the azulene unit to NDTI.The E_HOMO values of NDTI-B2Az and NDTI-B6Az were then estimated to be–5.89 and–6.13 e V by photoelectron spectroscopy in air（PESA）,respectively.Under ambient conditions,the OFET devices based on NDTI-B2Az showed ambipolar transfer characteristics with high electron and hole mobilities of 0.32 and 0.03 cm² V-¹ s-¹,respectively,whereas a typically unipolar n-type behavior is found for the OFET device bansed on NDTI-B6Az with a high electron mobility up to 0.13 cm² V-¹ s-¹.3.The compound NDTI-BTIC1 containing noncovalent intramolecular S···Ointeractions and its corresponding contrast compound NDTI-BTIC2 were successfully synthesized,in where an electron deficient NDTI-core and two electron deficient3-（dicyanomethylidene）-indan-1-one（IC）groups were covalently connected with thiophene substituted by alkoxy chain or alkyl chain,respectively.By two-dimensional grazing incidence wide-angle X-ray scattering（2D-GIWAXS）analysis and atomic force microscopy（AFM）measurement,the NDTI-BTIC1 film has good crystallicity and more ordered structure,and the molecules are stacked perpendicular to the substrate（edge-on）,which is beneficial to carrier transport.The maximum electron mobility of NDTI-BTIC1（0.17 cm² V-¹s-¹）is one order of magnitude higher than that of NDTI-BTIC2（0.085 cm² V-¹s-¹）.4.Three new dithienocoronenediimide（DTCDI）-derived triads,DTCDI-BT,DTCDI-BBT and DTCDI-BNT,were designed and synthesized.DFT calculations reveal that the HOMO energy levels of the three triads compared to that of the parent DTCDI-core（-5.99 e V）are significantly increased to–5.59,–5.59 and–5.45 e V for DTCDI-BT,DTCDI-BBT and DTCDI-BNT,respectively.In fact,under ambient atmosphere,solution-processed bottom-gate top-contact（BGTC）transistors exhibit ambipolar charge transport properties by tuning the HOMOs of the DTCDI-based triads suitable for hole injection,resulting in a balanced maximum electron and hole mobilities of 1.66×10-³ and 1.02×10-³ cm² V-¹s-¹ for DTCDI-BT,2.60×10-² and 3.60×10-² cm² V-¹s-¹ for DTCDI-BBT,and 2.43×10-³ and 4.15×10-³ cm² V-¹s-¹ for DTCDI-BNT,respectively.This is the first time that the DTCDI building block has been used to develop ambipolar small molecular semiconductors.Additionally,DTCDI-BBT-based complementary-like inverters were tried to make preliminarily,the inverter devices operated well in both p-mode and n-mode under ambient conditions.5.Two isomers DTCDI-B2Az and DTCDI-B6Az are synthesized,in which two azulene units were connected with DTCDI at the 2-position of the azulene ring in DTCDI-B2Az,whereas two azulene units were incorporated with DTCDI at the6-position of the azulene ring in DTCDI-B6Az.The DFT theoretical calculations and photochemical studies show that the two isomers may have different carrier transport characteristics.Solution-processed bottom-gate top-contact（BGTC）transistors based on thin film of the triads were constructed,under ambient atmosphere,DTCDI-B2Az exhibits ambipolar characteristics with the maximum electron and hole mobility of1.83×10-² and 5.40×10-⁴ cm² V-¹s-¹,respectively.DTCDI-B6Az exhibits unipolar n-type semiconductor transport behavior and maximum electron mobility is 1.56×10-² cm² V-¹s-1.