The influence of the capping ligands on the optoelectronic performance, morphology, and ion liberation of CsPbBr3 perovskite quantum dots

• Published in: Nano research Vol. 16; no. 7; pp. 10626 - 10633
• Main Authors: Liu, Yongfeng, Tang, Shi, Gao, Zhaoju, Shao, Xiuwen, Zhu, Xiaolin, Ràfols Ribé, Joan, Wågberg, Thomas, Edman, Ludvig, Wang, Jia
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01.07.2023; Springer Nature B.V
• Subjects: Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Capping; Chemistry and Materials Science; Condensed Matter Physics; Density; Electric fields; Electrochemical cells; Electrochemistry; Electrolytes; Ligands; Materials Science; Nanotechnology; Octanoic acid; Optoelectronics; Perovskites; Photoluminescence; Photons; Quantum dots; Research Article; Thin films; Toluene; quantum dots; light-emitting electrochemical cell; capping ligand; ion liberation; CsPbBr
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-023-5589-y

Perovskite quantum dots (PeQDs) endowed with capping ligands exhibit impressive optoelectronic properties and enable for cost-efficient solution processing and exciting application opportunities. We synthesize and characterize three different PeQDs with the same cubic CsPbBr 3 core, but which are distinguished by the ligand composition and density. PeQD-1 features a binary didodecyldimethylammonium bromide (DDAB) and octanoic acid capping ligand system, with a high surface density of 1.53 nm −2 , whereas PeQD-2 and PeQD-3 are coated by solely DDAB at a gradually lower surface density. We show that PeQD-1 endowed with highest ligand density features the highest dispersibility in toluene of 150 g/L, the highest photoluminescence quantum yield of 95% in dilute solution and 59% in a neat film, and the largest core-to-core spacing in neat thin films. We further establish that ions are released from the core of PeQD-1 when it is exposed to an electric field, although it comprises a dense coating of one capping ligand per four surface core atoms. We finally exploit these combined findings to the development of a light-emitting electrochemical cell (LEC), where the active layer is composed solely of solution-processed pure PeQDs, without additional electrolytes. In this device, the ion release is utilized as an advantage for the electrochemical doping process and efficient emissive operation of the LEC.