Related Experiment Video
Updated: Apr 8, 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
10.2K
Halide Segregation Induces Carrier Funneling and Polaron Mode Modulation in Mixed-Halide Perovskites.
Xinzhi Zu1,2,3, Jingjing Yang2, Weiqi Chen2
1State Key Laboratory of Ultra-intense laser Science and Technology, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
The Journal of Physical Chemistry Letters
|April 7, 2026
Summary
Mixed-halide perovskites show carrier funneling due to halide segregation, forming dense reservoirs. This impacts polaron dynamics and electron-phonon coupling, affecting optoelectronic device performance.
Area of Science:
- Materials Science
- Solid-State Physics
- Optoelectronics
Background:
- Mixed-halide perovskites offer tunable bandgaps but face stability issues from light-induced halide segregation.
- The effect of phase segregation on polaron dynamics and electron-phonon coupling in these materials is not well understood.
Purpose of the Study:
- To investigate the influence of halide segregation on carrier transport and polaron evolution in mixed-halide perovskites.
- To elucidate the microscopic mechanisms behind performance loss in perovskite optoelectronics.
Main Methods:
- Combined optical pump-terahertz probe spectroscopy and microscale transient reflection microscopy.
- Achieved simultaneous temporal and spatial resolution of carrier dynamics and polaron behavior.
Main Results:
- Identified subpicosecond carrier funneling from Br-rich to I-rich domains, creating high-density carrier reservoirs within 20 ps.
- Observed enhanced polaron-polaron overlap and strengthened anharmonic electron-phonon coupling due to localized carrier accumulation.
- Detected a blue shift in polaron resonance, increased oscillator strength, and shortened phonon lifetime.
Conclusions:
- Early-stage halide segregation primarily renormalizes polaron modes via carrier spatial accumulation, not intrinsic transport degradation.
- Provides mechanistic insight into performance loss in mixed-halide perovskite optoelectronics.
Related Concept Videos
01:22Carrier Generation and Recombination
1.6K
Carrier generation is the process by which electron-hole pairs (EHPs) are created within the semiconductor. In direct-bandgap semiconductors, such as gallium arsenide (GaAs), this occurs efficiently when energy absorption prompts valence electrons to leap into the conduction band, leaving behind holes.
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
1.6K
02:46Halogenation of Alkenes
21.2K
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.
21.2K
01:11P-N junction
1.7K
A p-n junction is formed when p-type and n-type semiconductor materials are joined together. At the interface of the p-n junction, holes from the p-side and electrons from the n-side begin to diffuse into the opposite sides due to the concentration gradient. This diffusion of carriers leads to a region around the junction where there are no free charge carriers, known as the depletion region. The charge density within the depletion region for the n-side and p-side can be described by the...
1.7K
01:24Metal-Semiconductor Junctions
1.4K
The contact of metal and semiconductor can lead to the formation of a junction with either Schottky or Ohmic behavior.
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The...
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The...
1.4K
01:21Carrier Transport
1.2K
The generation of electrical current in semiconductors is fundamentally driven by two mechanisms: drift and diffusion. These processes are essential for the functionality and performance of semiconductor-based devices.
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by:
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by:
1.2K
01:27Biasing of Metal-Semiconductor Junctions
837
Biasing metal-semiconductor junctions involves applying a voltage across the junction. Specifically, the metal is connected to a voltage source, while the semiconductor is grounded. This technique is essential for controlling the direction and magnitude of current flow in electronic devices, including diodes, transistors, and photovoltaic cells.
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
837