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Surface Ligand Engineering-based Performance Modulation And Optoelectronic Applications Of Perovskite Nanocrystals

Posted on:2024-02-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y ZhaoFull Text:PDF
GTID:1521307319462794Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Perovskite nanocrystals(PNCs)are widely used in optoelectronic devices,benefiting from their high defect tolerance,tunable emission wavelength,high photoluminescence quantum yield,and multi-exciton effect.Solution-based perovskite nanocrystals require surface passivation ligands binding to the surface of nanocrystals to control the size,morphology,structure stability,charge transfer and optical properties of PNCs.Based on the surface ligands engineering,this thesis aims to figure out the influence of the ligand molecular structure and the interaction between ligands and PNCs on the optoelectronic properties and stabilities of PNCs.Meanwhile,the ligand-modified PNCs are applied in the optoelectronic field.The details are as follows:(1)The non-conjugated organic radical polymers,poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate)(PTMA)and poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl)(PTEO)have been used to replace the oleylamine and oleate on the surface of CsPbBr3 nanocrystals and to investigate the effect of the radical polymers on the charge transfer ability and stability of PNCs.The results showed that PTEO and PTMA could significantly enhance the stabilities involved the humidity,thermal and illumination stability.And the charge transfer processes between the radical polymers and PNCs were observed.Finally,combined with UV illumination stability and charge transfer ability,the PTEO-PNCs may photodegrade chlorobenzene under 365 nm UV light,realizing the halogen exchange with sp2 hybrid covalent halide.(2)A surface post-treatment on PNCs was demonstrated by introducing the X-type ligand,1,3-bisbenzyl-2-oxoimidazolidine-4,5-dicarboxylic acid(cycle acid,CA).And the effect of CA on the morphology,optical properties and stabilities of PNCs were investigated.The results indicated that the etching and passivation of CA could effectively suppress the surface defects of PNCs,homogenize the morphology,and improve the photoluminance quantum yield and stabilities of PNCs.In addition,CA could repair the structure of PNCs resulting in the fluorescence recovery of CsPbX3 PNCs.Finally,the white light emitting diode(WLED)was fabricated based on CA-PNCs including CsPbBr3 and CsPbIxBr3-x PNCs.The WLED exhibited excellent luminescent performance with a color coordinate of(0.41,0.40),a color rendering index(CRI)of 81.2,a power efficiency of 15.06 lm W-1,and a color gamut that can cover almost 120%of NTSC color.The stability of this device also improved.(3)The ligand-modified CsPbBr3 nanocrystals,CA-CsPbBr3 and PTMA-CsPbBr3,were used to synergistically modulate key interfaces and functional layers of perovskite solar cells(PSCs)to fabricate the efficient and stable PSCs.First,CA-CsPbBr3 modulated the interface of perovskite/hole transport layer(HTL),which not only selectively removed unreacted lead iodide residues from the surface of perovskite,optimized the surface morphology and passivated the defects at the grain boundaries of the perovskite film,but also enables a well-matched interfacial energy level between the perovskite and HTL.Besides,the highly photoactive PTMA-CsPbBr3 was used as an additive to modulate the electrical properties and stabilities of the HTL.This method can significantly improve the hole mobility and conductivity,and enhance the moisture stability of the HTL.Through the synergistic modulation strategy of CA-CsPbBr3 and PTMA-CsPbBr3,the power conversion efficiency of PSC increased from 20.06%to 22.15%and the stabilities enhanced that can maintain 78%of its original PCE under ambient conditions at 60%relative humidity aged for about 1400 h.
Keywords/Search Tags:Perovskite nanocrystal, Surface ligand engineering, Optoelectronic properties, Stability, Photodegradation, Photoluminescence devices, Solar cell
PDF Full Text Request
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