| 1. |
- Ghosh, Supriya, et al.
(författare)
-
Light-induced defect healing and strong many-body interactions in formamidinium lead bromide perovskite nanocrystals
- 2020
-
Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 11:4, s. 1239-1246
-
Tidskriftsartikel (refereegranskat)abstract
- Organic lead halide perovskite (OLHP) nanocrystals (NCs) have paved the way to advanced optoelectronic devices through their extraordinary electrical and optical properties. However, understanding of the light-induced complex dynamic phenomena in OLHP NCs remains a subject of debate. Here we used wide field microscopy and time-resolved spectroscopy to correlate the local changes in photophysics and the dynamical behavior of photocarriers. We demonstrate that light-induced brightening of the photoluminescence from the formamidinium lead bromide NC films is related to the film preparation condition and reduction of trap density. The density of trap states is reduced via halide ion migration from interstitial position. Our femtosecond transient absorption study identifies transient Stark effect due to the generation of hot carriers. Because of slow carrier trapping, Auger recombination through many-body carrier-carrier interactions dominates over trion recombination. This work presents unprecedented insights into the light-driven processes enabling better device design in the future.
|
|
| 2. |
- Ghosh, Supriya, et al.
(författare)
-
Phonon Coupling with Excitons and Free Carriers in Formamidinium Lead Bromide Perovskite Nanocrystals
- 2018
-
Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 9:15, s. 4245-4250
-
Tidskriftsartikel (refereegranskat)abstract
- Organometal halide perovskites in the form of nanocrystals (NCs) have attracted enormous attention due to their unique optoelectronic and photoluminescence (PL) properties. Here, we examine the phase composition and the temperature dependence of emission line width broadening in formamidinium lead bromide (FAPbBr3) perovskite nanocrystals (NCs) for light-emitting applications and identify different charge-carrier scattering mechanisms. Our results show most of the emission is from the orthorhombic phase. The PL line width broadening at high temperature is dominated by the Fröhlich interaction between the free charge carriers and the optical phonons. At low temperatures, the peak of the PL spectrum exhibits a continuous red shift indicating an increase of excitons contribution at lower temperatures, and concurrently the line width also narrows down due to the inhibition of the optical phonons. From the temperature-dependent measurements, the coupling strength of both the charge phonon interaction and the exciton phonon interaction have been determined. The obtained results indicate that the charge phonon coupling strengths are higher compared to the exciton phonon coupling.
|
|
| 3. |
- Li, Hu, 1986-, et al.
(författare)
-
Enhanced gas sensing performance of graphene/ZnS-CdS hetero-nanowires gas sensor synthesized by Langmuir-Blodgett self-assembly method
- 2017
-
Ingår i: Journal of Physics Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 922
-
Tidskriftsartikel (refereegranskat)abstract
- Graphene is a promising material in the field of solid-state gas sensors due to the unique two-dimensional structure. Here, we have shown by fabricating graphene/ZnS-CdS hetero-nanowire structure, the gas sensor sensitivity has a two-fold increase to 20% under 15 ppm gaseous concentration compared to a 10% response in pristine graphene. Spectroscopy and microscopy analysis indicate that the semi-conducting ZnS-CdS hetero-nanowires are 2 nm wide and densely packed on top of graphene. By combining UV illumination, the device approaches a fast response/recovery and high gas sensitivity, thus has a potential to be used in a detection of wide range of gases.
|
|
