Photostability of amine-free CsPbBr3 perovskite nanocrystals under continuous UV illumination

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Bonato, Luiz Gustavo ; Dal Poggetto, Guilherme ; Moral, Raphael Fernando ; de Carvalho Vale, Brener Rodrigo ; Germino, Jose Carlos ; Almeida, Diogo Burigo ; Santiago, Patricia ; Fernandez, Pablo Sebastian ; Tormena, Claudio Francisco ; Padilha, Lazaro A. ; Nogueira, Ana Flavia

• Document type: Journal article
• Source: JOURNAL OF MATERIALS CHEMISTRY C; v. 11, n. 24, p. 12-pg., 2023-03-06.

Abstract

Despite all the recent progress on understanding the optoelectronic and structural properties of the CsPbX3 perovskite nanocrystals (PNCs), the impact of the ligands on their photostability, under continuous UV light soaking, is still ambiguous. To address this subject, in this work, we have investigated the influence of the organic ligand on the photophysics of PNCs by comparing the emission behaviour of CsPbBr3 PNCs capped with oleate (OA) and oleylphosphate (OPA). Based on our experimental observations, we propose two different mechanisms to explain their photostability under continuous UV illumination. We hypothesize that the UV illumination promotes a reconstruction of the nanocrystals' surface, and this process depends on the equilibrium between desorption and adsorption of the surface ligands. In the case of oleate-capped PNCs, this reconstruction is delayed, and even hampered, due to the steric hindered Pb-oleate that desorbs from the surface. In contrast, for the oleylphosphate-caped PNCs, the detached Pb-oleylphosphate can re-adsorb to the surface soon after it leaves because the steric effects are less critical. The results reported here suggest that alkylphosphate ligands can be used to improve the photostability of colloidal PNCs dispersions, an important step towards applications that require continuous excitation, such as back-illuminated LEDs and solar cells. (AU)

• FAPESP's process: 20/10246-0 - Nuclear magnetic resonance spectroscopy: from pulse sequences to structural assignments
• Grantee: Claudio Francisco Tormena
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 21/13262-0 - Synthesis of Novel Perovskite Nanostructures
• Grantee: Luiz Gustavo Bonato
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/11986-5 - Generation and storage of New Energy: bringing technological development for the country
• Grantee: Ana Flávia Nogueira
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 20/16077-6 - Ultrafast spectroscopy applied to heavy metal-free semiconductor nanocrystal materials
• Grantee: Brener Rodrigo de Carvalho Vale
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 18/15574-6 - Advanced spectroscopy of nanomaterials: from ensemble to single-particle
• Grantee: Lázaro Aurélio Padilha Junior
• Support Opportunities: Research Grants - Young Investigators Grants - Phase 2
• FAPESP's process: 19/22576-8 - Accessing the excited state dynamics in nanostructures by multidimensional coherent spectroscopy
• Grantee: Diogo Burigo Almeida
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 19/25765-6 - In situ experiments with synchrotron based SAXS and WAXS to probe reactions and formation mechanisms of trending (nanostructured) lead halide materials
• Grantee: Raphael Fernando Moral
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 20/04431-0 - Perovskite oxides for the continuous and/or simultaneous production of energy and/or dense energy carriers
• Grantee: Pablo Sebastián Fernández
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Regular Program Grants