Structural Characterization And Study On Photoelectric And Photothermal Properties Of Novel Curved Polycyclic Aromatic Hydrocarbons

In recent years,organic electronics has become a key focus area for researchers due to its wide range of material sources,low costs,and flexibility.Compared to inorganic materials,organic materials can achieve a variety of optoelectronic properties through rational molecular design,such as semiconductor materials,photo thermal and photochromic materials.Furthermore,the saturated frontier electronic properties of organic semiconductor materials result in inherently fewer defects in disordered systems compared to amorphous inorganic semiconductors.Lastly,organic materials can be prepared through cost-effective,efficient solution methods and exhibit excellent compatibility with flexible substrates,enabling the manufacture of large-area flexible electronics.Molecular structures,packing structures,and crystal morphologies are important factors that affect device performance.Different molecular structures will form unique packing structures based on various intermolecular interactions.Different packing structures also significantly affect the morphology of crystals,which in turn affects photoelectric performance.Curved polycyclic aromatic hydrocarbons(PAHs)have attracted widespread attention due to their high solubility,unique optoelectronic and chemical properties,but there are relatively few studies on the assembly behavior and optoelectronic properties of curved PAHs.Based on curved polycyclic aromatic hydrocarbons,the effects of substituents and nonbenzenoid on their crystal structures,assembly behaviors,optoelectronic properties,and photothermal conversion characteristics were studied in this paper.The specific research work is as follows:1.A new C2v symmetric structure,1,and its derivatives were studied.Single crystal tests showed that different substituents not only affected the molecular curvature but also significantly influenced the packing motifs,resulting in a profound difference in device performance.The single crystal mobility of π-bowl 1 is 2.30 cm2 V-1 s-1 and that of π-bowl 2 is 1.16 cm2 V-1 s-1,which is the highest mobility of organic π-bowl semiconductors.The π-bowls 1 and 2 form two-dimensional organic cocrystals with C70 molecules.The C70 molecules aggregated into one-dimensional linear and zig-zag arrays.Notably,the electron mobility of 0.16 cm2 V-1 s-1 was measured in the cocrystal.Finally,cocrystal 1-C70 displayed good photo-responsive properties with a responsivity of 10 mA·W-1,which further demonstrates the application potential of these materials in optoelectronic devices.2.Two kinds of curved polycyclic aromatic hydrocarbons with different substituent groups were studied,and the effect of α-position substituents on the preparation of cocrystals was investigated.Single crystal data analysis revealed that due to steric hindrance at the α-position,Tri-Ben formed an angle close to 90° with buckybowls.This limited the concave-convex π-πinteractions with C70 molecules,preventing the formation of stable organic cocrystal structures.In contrast,the tert-butylbenzene groups in Ter-Ben had greater flexibility,allowing them to adjust to stable conformations during selfassembly,which resulted a network cocrystal structure with ambipolar transport characteristics with the highest hole and electron mobilities of 0.015 cm2 V-1 s-1 and 0.01 cm2 V-1 s-1,respectively.This study demonstrates that theα-position structure of phenyl substituents plays a crucial role in the formation and performance of cocrystals.3.The assembly behavior and carrier transport performance of new curved polycyclic aromatic hydrocarbons containing five-membered and eight-membered rings were studied.Compounds 5 and 6 exhibited both helicity and positive/negative curvature.In particular,due to its geometrically and electronically complementary nature,compound 6 could combine with C60 to form an organic cocrystal 6-C60.The OFET performance of 4-6 could be tuned with eight-membered rings.Compounds 5 and 6 showed ambipolar characteristics with hole and electron mobilities of 0.036 cm2 V-1 s-1 and 0.03 cm2 V-1 s-1,respectively.Additionally,an inverter based on compound 6 achieved a gain of 12.The cocrystal 6-C60 also exhibit ambipolar characteristics with electron and hole mobilities of reached as high as 0.19 and 0.11 cm2 V-1 s-1,respectively.These findings provide valuable design principles and experimental basis for the development of novel curved PAH materials with excellent optoelectronic properties.4.The carrier transport and photothermal conversion performance of rippled polycyclic aromatic hydrocarbons 7 and 8 with various nonbenzenoid rings were studied.These compounds exhibited high solubility,stable configurations,narrow bandgaps(1.25 eV and 1.12 eV),and ambipolar transport characteristics.The highest hole and electron mobilities of compounds 7 and 8 were 0.05 cm2 V-1 s-1/0.01 cm2 V-1 s-1 and 0.04 cm2 V-1 s1/0.002 cm2 V-1 s-1,respectively.Furthermore,compound 7 exhibited excellent photothermal conversion properties,rapidly heating to 316.60℃ under 808 nm laser irradiation.The photothermal conversion efficiency of compound 7 was up to 63.25%.Utilizing this property,we fabricated a light-driven device,that enabled linear or curved motion control of PDMS-7 film.These findings not only provided a class of potential materials for organic electronics and optoelectronics,but also laid a solid foundation for subsequent material design.