Inorganic halide perovskite nanocrystals have been a center of attention over the last few years due to their ease of preparation, easily tunable bandgap via anion exchange, narrow emission widths, and high quantum yield. These qualities make them extremely valuable in optoelectronics such as sensors, solar cells, photodetectors, and light-emitting diodes (LEDs). However, their rational development has been hindered due to difficulties in their purification, instability, limited understanding of their surface chemistry, and the dynamic nature of their lattice ions and surface ligands. Didodecydimethyl ammonium bromide (DDAB) is one of the most studied ligands used for the effective passivation of these nanocrystals. While some researchers have reported this ligand as an effective way of passivating the surface thus improving their stability, others have also reported it to cause a phase transformation from highly luminescent 3D CsPbBr3 to non-luminescent layered CsPb2Br5. Here, we report the preparation of highly stable DDAB-protected CsPbBr3 with a near-unity quantum yield that can be isolated using gel permeation chromatography (GPC). Furthermore, using isothermal titration calorimetry (ITC) coupled with complementary spectroscopic analysis, we have been able to resolve two different reactions that occur when DDAB is introduced, one leading to beneficial ligand exchange and a second that ultimately leads to the non-luminescent phase, thus resolving the conflicts in literature on the actual role of DDAB on the surface of perovskite nanocrystals.

Surface chemistry and thermodynamic investigation of CsPbBr3 nanocrystals via isothermal titration calorimetry

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.