This indicates a very small value of x in the end product. Hence, anisotropic crystal growth can be promoted by forcing further delivery of precursor reagents along the perpendicular axis. While finalizing the manuscript, a paper by Levchuk et al. The Journal of Physical Chemistry C , 11 , Mopelola A. Chobert G, Devaud M J.
Briefly, the lead iodide PbI2 and methylammonium iodide MAI precursor solution in acetonitrile is injected into the toluene solution containing the capping agents under vigorous stirring. Zhibo Yao, Timothy W. This complete transformation to a pure-iodide based perovskite is reasonable since prolonged heating often results in undetectable chlorine content, both observed in our investigations and in the literature Full size image The photocurrent density-voltage responses of the devices Fig. The intensive investigations have accumulated rich experiences in the perovskite fabrication; while the mechanism of the chemical synthesis still remains unresolved. An overall result is that the reaction rate did not show increment along with the increase of reactant amount.
After stirring for four hours, a dark brown suspension of perovskite NCs in toluene is obtained.
Pathak et al. The Journal of Physical Chemistry C , 35 , After sufficiently pre-drying the perovskite precursor solution containing PbI2 and CH3NH3I at 60 oC, the yielded light yellow powder was heated at elevated temperature to facilitate the reaction. Five minutes after injection of 1. Ross, and Chad A.
Afterwards, we analyze the reaction from both thermodynamic and kinetic perspectives and discover their impacts on film formation behavior. To explore the reaction pathways, we apply in situ XRD to probe the crystal structure evolution—associated intermediate chemical reactions. If we assume that the overall reaction is described by reaction 9 below, a complete transformation to the perovskite leads to a weight loss of Figure 5: Morphological characterization of the active layer and device cross section. ACS Energy Letters , 2 3 ,
Noden FG The determination of tetraalkyllead compounds and their degradation products in natural water.
Journal of the American Chemical Society , 40 , Harrison GF The Cavtat incident. The diffraction pattern cannot be assigned to any perovskite or the precursor material. This is a typical characteristic of the solid-state reaction involving gaseous product generation. When the precursor film is annealed in an atmosphere containing NH3, the process is greatly accelerated and the reaction completes within 2 min Supplementary Fig. Wiley A.
Furthermore, annealing of the yellow sample can again lead to the formation of the perovskite, indicating that the reaction between PbCl2 and CH3NH3I is reversible.
Here, we set up the chemical equation of the synthesis and elucidate the reactions from both thermodynamic and kinetic perspectives. Five minutes after injection of 1. The final suspension was maintained in the dark. Unger, Ivan G. The photoluminescence quantum yields QY were recorded on an Edinburgh FLS fluorimeter, which was been extended with an external integrated sphere from Labsphere connected to the fluorimeter via optical fibers see Figure S Tiravanti G, Boari G Environ.
Herein, we combine the two reaction kinetics together to find an optimal crystallinity.