Phase‐Stable CsPbI3 Nanocrystals: The Reaction Temperature Matters

• Published in: Angewandte Chemie Vol. 130; no. 29; pp. 9221 - 9225
• Main Authors: Dutta, Anirban, Dutta, Sumit K., Das Adhikari, Samrat, Pradhan, Narayan
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 16-07-2018
• Subjects: Additives; Ammonium; Chemical synthesis; Chemistry; Crystal lattices; Crystals; CsPbI3; Emission analysis; High temperature; Inert atmospheres; Kolloidale Stabilität; Ligands; Nanocrystals; Optical materials; Perovskites; Perowskit-Nanokristalle; Phase transitions; Phasenstabilität; Surface stability; Temperature effects; Thermische Stabilität
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201803701

High temperature colloidal synthesis for obtaining thermal, colloidal and phase‐stable CsPbI3 nanocrystals with near‐unity quantum yield is reported. While standard perovskite synthesis reactions were carried out at 160 °C (below 200 °C), increase of another ≈100 °C enabled the alkylammonium ions to passivate the surface firmly and prevented the nanocrystals from phase transformation. This did not require any inert atmosphere storage, use of heteroatoms, specially designed ligands, or the ice cooling protocol. Either at high temperature in reaction flask or in the crude mixture or purified dispersed solution; these nanocrystals were observed stable and retained the original emission. Different spectroscopic analyses were carried out and details of the surface binding of alkyl ammonium ligands in place of surface Cs in the crystal lattice were investigated. As CsPbI3 is one of the most demanding optical materials, bringing stability by proper surface functionalization without use of secondary additives would indeed help in wide spreading of their applications.
Erwärmen hilft: Konventionelle Synthesen phasenstabiler CsPbI3‐Nanokristalle werden unterhalb von 200 °C durchgeführt. Eine Temperaturerhöhung auf über 240 °C führt zur Stabilisierung der Größe, Form und Phase. Analysen zeigen, dass hohe Temperaturen die Passivierung der Oberfläche mit Alkylammoniumionen begünstigen, sodass der Kristall seine Form behält.