Related Experiment Video
Updated: Feb 17, 2026
08:12
Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films
Published on: September 8, 2017
10.1K
Post-synthetic halide conversion and selective halogen capture in hybrid perovskites
D Solis-Ibarra1, I C Smith1, H I Karunadasa1
1Department of Chemistry , Stanford University , Stanford , CA 94305 , USA .
Chemical Science
|December 9, 2017
Summary
Researchers developed a simple gas-solid reaction to convert lead-iodide perovskites into lead-bromide or lead-chloride films. This method retains perovskite crystallinity for optoelectronic applications.
Area of Science:
- Materials Science
- Chemistry
Background:
- Metal-halide perovskites are crucial for optoelectronics.
- Post-synthetic modification of perovskites is challenging.
Purpose of the Study:
- To develop a novel method for halide exchange in perovskites.
- To investigate halogen reactivity in both 3D and 2D perovskites.
Main Methods:
- Exposure of 3D perovskite films to Br2 or Cl2 gas.
- Reaction of 2D perovskites with terminal alkene groups to Br2 gas.
- Analysis of structural and chemical changes.
Main Results:
- Clean conversion of 3D Pb-I to Pb-Br or Pb-Cl perovskite films.
- Chemisorption of Br2 by organic layers in 2D perovskites.
- Selective Br2 capture for high-purity I2 gas streams.
- Halogen transfer between inorganic and organic layers.
- Retention of perovskite crystallinity during structural rearrangement.
Conclusions:
- Gas-solid halogen exchange is a viable method for perovskite modification.
- This technique enables the synthesis of high-quality optoelectronic materials.
- The process offers unique applications in gas purification and materials science.
Related Concept Videos
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
11.5K
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
11.5K
02:46Halogenation of Alkenes
19.3K
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
19.3K
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
17.5K
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
17.5K
00:51Base-Promoted α-Halogenation of Aldehydes and Ketones
4.3K
α-Halogenation of aldehydes and ketones is a reaction involving the substitution of α hydrogens with halogens in the presence of a base. The reaction begins with the abstraction of α hydrogen by the base to produce a nucleophilic enolate ion. This intermediate undergoes a subsequent nucleophilic substitution with the halogen to produce a monohalogenated carbonyl compound. If the starting substrate has more than one α hydrogen, it is difficult to stop the reaction...
4.3K
02:35Regioselectivity of Electrophilic Additions-Peroxide Effect
11.1K
In the presence of organic peroxides, the addition of hydrogen bromide to an alkene yields the isomer that is not predicted by Markovnikov’s rule. For example, the addition of hydrogen bromide to 2-methylpropene in the presence of peroxides gives 1-bromo-2-methylpropane. This addition reaction proceeds via a free radical mechanism, which reverses the regioselectivity. The free radical reaction mechanism involves three stages: initiation, propagation, and termination.
11.1K
01:11Reactions at the Benzylic Position: Halogenation
3.7K
Benzylic halogenation takes place under conditions that favor radical reactions such as heat, light, or a free radical initiator like peroxide.
3.7K