The Study On The Synthesis And Properties Of Cyanostyrene Compounds

Since 2009,perovskite solar cells（PSCs）have made a great progress.The power conversion efficiency（PCE）of PSCs is beyond 25%in decades.Hole transport layers plays an important role in PSCs,which can inhibit the interfacial electron recombination effectively,extract holes and improve the stability of the devices.Exploring the influencing factors of high efficiency of HTMs and applying to develop a new kind of that materials are essential.In this paper,we changed CN group sites to adjust the fluorescent properties of hole transport materials,and applied them in i-PSCs,explored the structure-activity relationship between fluorescent properties and cell devices,obtained a satisfied PCE.（1）Three kinds of simple and efficient"D-A-D"structure organic small molecule hole transport materials,YJ01、YJ02 and YJ03 were designed and synthesized with Cyanostilbenes as the core.Physical and photoelectrochemical properties were tested mainly on YJ01 and YJ02.According to UV-FL spectra and CV curve,the energy levels of the two materials were calculated to match the perovskite.The surface roughness of the hole transport layers was measured,so did the contact angle of the precursor and hydrophobic angle with the hole transport layers.Density functional theory calculations found that the electron cloud distribution within the molecules of the two materials is quite different,and the electron arrangement of YJ01 is more reasonable.The maximum absorption wavelength of ultraviolet and visible light of the two materials is the same,and the fluorescence emission wavelength is significantly different.（2）To further explored the optical differences between the two materials and their influence on hole transport.By analyzing the aggregation-induced emission（AIE）performance of the two in the THF/H2O system,it is found that YJ02 has the highest fluorescence intensity when the H2O content is 90%,and YJ01 only shows weak fluorescence under the same conditions.The fluorescence quantum yield results show that core1 under the same excitation wavelength exhibits a higher quantum yield.The YJ01,which uses it as core,has obvious fluorescence quenching,and the quantum yield drops to 0.25%,which is lower than YJ02’s 2.49%.The hole mobility of two materials was prepared without doped hole transport layer film,which proved that YJ01 has higher hole mobility and can better promote hole-electron pair separation.（3）Two kinds of materials were applied in the inverted perovskite solar cells by"one-step deposition method"to gain their PCE results.Unsurprisingly,the devices with YJ01 as HTM showed better performance,the undoped PCE reached 19.85%,the fill factor（FF）is 0.815,the short circuit current（JSC）is 22.53 m A/cm^-2,the open circuit voltage（VOC）is 1.08 e V,while the YJ02 barely reached 17.5%.The transient and steady-state test results show that YJ01 has stronger fluorescence quenching and shorter electron lifetime,which proves that YJ01 with higher quantum yield of the core and a more distorted molecular structure,can be dedicated to the preparation of high efficiency of i-PSCs.（4）Three new types of fluorene-based hole transport materials YJ-OF1,YJ-OF2and YJ-OF3 were designed and synthesized to explore the influence of different side chains on the film morphology.By changing the anisole in diphenylamine to dimethyl fluorene,the molecular planarity is increased to improve the film-forming properties.