Theoretical Study On Charge Transfer Properties Based On Naphthalenetetraformyldiimide (NDI) Organic Semiconductors

Organic semiconductor（OSC）materials are widely used in the field of optical and electrical components because of their low price,light weight,foldable and easy processing.At present,a large number of p-type（hole transporting）organic semiconductor materials with good properties and stability have been reported,and their development is relatively mature,while n-type（electron transporting）organic semiconductor materials have poor electron injection ability and are easy to be oxidized in the environment,so the development is lagging behind.But it is well known that n-type organic materials are an essential part of logical complementary circuits.Therefore,the design of n-type semiconductor with high mobility plays an important role in promoting the rapid development of optoelectronic devices.In this paper,several typical n-type organic semiconductor materials with different core structures of amide substituents are studied.The charge transport properties of these materials are systematically calculated and analyzed by using the first principles.The influences of different core structures on the transport properties of materials are illustrated from the aspects of single molecule structure characteristics,intermolecular stacking modes and intermolecular interactions.The results show that the series of molecules studied are electron transport materials（n-type materials）,and have good air stability.Among them,molecule A2with a linear arrangement of central benzene rings have relatively higher electron affinity（EA）values,and therefore have the best air stability.In addition,we found that although the reorganization energy ofπexpansion along the long axis andπexpansion along the short axis decreased,it was found that the reduction in high and low frequency regions was different when projected into the regular mode.Compared to molecule A1,molecule A2 obtained byπexpansion along the short axis effectively suppress the vibration of molecule in the high-frequency region;The molecules A3 and A4 that extend along the long axisπsuppress the vibrations of the molecule in the low frequency region.Finally,the nearest neighbor dimer stacking patterns in a series of molecular crystals were analyzed,and it was found that the dimers of A3 and A4extending along the long axisπhad a small short axis slip,exhibiting two-dimensional electron transport materials,with two-dimensional average electron mobility as high as0.06 cm²V^-1s^-1 and 0.15 cm²V^-1s^-1;The dimer stacking of molecule A2 that extend along the short axisπhas a large short axis slip,and therefore behaves as a one-dimensional electron transport material.Its one-dimensional electron mobility is calculated to be0.96 cm² V^-1 s^-1.In this paper,the relationship between molecular structure-intermolecular stacking model-electron transport properties of several typical n-type organic semiconductor materials containing different core structures of amide substituents is analyzed by theoretical calculation and simulation,which provides certain design ideas and clues for the design of stable high-performance electronic transport materials.