| As a rising star in the field of solar cells,perovskite solar cells（PSCs）have achieved rapid development in the past decade and become the most commercially promising new solar cells after silicon cells.PSCs are mainly composed of transparent conductive electrode,electron transport layer（ETL）,perovskite layer,hole transport layer（HTL）and metal counter electrode.As a key component of the battery,HTL plays an important role in extracting holes from the light-absorbing layer and blocking electron transport,while inhibiting charge recombination and protecting the perovskite layer from water and oxygen erosion.In recent years,PSCs based on organic hole transport materials（HTM）have become a hot research direction in the field of optoelectronic devices due to their high photoelectric conversion efficiency and low cost.Starting from the application requirements of ideal organic hole-transporting materials（HTMs）,this article uses Spiro[fluorene-9,9’-xanthrene]（SFX）,Spirobifluorene（SBF）,and Triphenylamine（TPA）as the skeletons and introduces structures such as carbazole,phenothiazine,and thiophene through rational design to synthesize high-hole-mobility organic small molecule HTMs.The photoelectric properties of the materials were tested and characterized and applied to PSCs devices.By testing the efficiency and stability of the device,the following experimental results are obtained:1)Compounds SBF-KZ and SFX-FEQ were synthesized by coupling reaction with SBF and SFX as the core and electron-rich carbazole and phenoxazine as peripheral substituents.The test results show that compared with the traditional material Sprio-OMe TAD,the hole mobility of the two materials is higher and the stability is better.It is found that the introduction of electron-rich substituents carbazole and phenoxazine can improve the hole mobility of the materials.The hole mobility of SBF-KZ and SFX-FEQ can reach 4.24×10-5 cm2 V-1 S-1 and 1.21×10-4 cm2 V-1 S-1,respectively,which is conducive to the extraction and transport of holes.The water contact angles of SBF-KZ and SFX-FEQ are 91°and 94°,respectively,which can effectively protect the perovskite materials from the erosion of water and oxygen.The device performance of the two materials was characterized.The test results show that the application of SBF-KZ and SFX-FEQ in PSCs can obtain device efficiency of 18.69%and 20.71%,and has good device stability.2)In order to further verify the excellent properties of carbazole substituents,we designed small molecule materials TCB and TCT with benzene and triphenylamine as cores and carbazole as peripheral substituents.The study found that triphenylamine has a more distorted spatial structure than the benzene ring,thus reducing the molecular accumulation,which is conducive to increasing the solubility of the material,thereby obtaining a higher quality film.The two kinds of materials TCB and TCT with carbazole groups have large hole mobility(TCB:2.92×10-4 cm2 V-1 S-1;TCT:3.14×10-4cm2 V-1 S-1).The PSCs devices based on TCB and TCT can obtain 17.5%and 18.15%device efficiency.The unpackaged TCB and TCT-based PSCs can still maintain more than 70%of the original efficiency after being placed in an environment with air humidity of 45%for 500 h,showing good device stability.3)Considering the excellent properties of triphenylamine,three kinds of compounds MPT,TPT and NBT with different end groups were synthesized by using triphenylamine as the core and introducing thiophene groups.The test results show that the three types of materials have appropriate energy levels and can match well with perovskite materials.It also has high hole mobility and hydrophobicity.The hole mobility of NBT reaches 7.73×10-5cm2 V-1 S-1,which is beneficial to the efficient extraction and transport of holes.The device performance of the three materials was tested.The results showed that MPTTPT and NBT with triphenylamine as the core were applied to PSCs to obtain photoelectric conversion efficiency of 19.56%,20.87%and 21.04%,respectively,and showed good device stability. |
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