Optimizing Band Gap of Inorganic Halide Perovskites by Donor–Acceptor Pair Codoping

2020 ◽  
Vol 59 (9) ◽  
pp. 6053-6059
Author(s):  
Atef Iqbal ◽  
Zijuan Sun ◽  
Gang Wang ◽  
Jun Hu
Keyword(s):  
Band Gap ◽  
Acceptor Pair ◽  
Donor Acceptor ◽  
Halide Perovskites ◽  
Donor Acceptor Pair

EL2-Induced Upconversion Luminescence In GaAs

1996 ◽  
Vol 442 ◽  
Author(s):  
V. Alex ◽  
T. Iino
Keyword(s):  
Band Gap ◽  
Upconversion Luminescence ◽  
Hot Electrons ◽  
Complete Disappearance ◽  
Acceptor Level ◽  
Acceptor Pair ◽  
Step Process ◽  
Regeneration Mechanism ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

AbstractNear band gap luminescence in bulk-grown semi-insulating GaAs is excited in a two step process via the EL2 defect. While the conventionally excited photoluminescence of our samples is dominated by conduction band to acceptor transitions, the upconversion process selectively excites donor acceptor pair transitions. Illumination near the maximum of the EL2- photoquenching band at 1064 nm leads to a complete disappearance of the so called upconversion photoluminescence (UPL). Excitation with light of shorter wavelengths however only partially quenches the UPL. Excitation between 850nm and 900nm completely regenerates the UPL. The characteristic photorecovery transients of the UPL are described by the EL2 regeneration mechanism via the population of the acceptor level of the metastable EL2 by hot electrons. The recovery of the EL2 by simultaneous illumination with above and below band gap light enables the observation of UPL at wavelengths, where the EL2-defect would otherwise be rapidly quenched. Under these conditions we observe a remarkable increase of the UPL-efficiency.

A novel complementary absorbing donor–acceptor pair in block copolymers based on single material organic photovoltaics

2014 ◽  
Vol 2 (9) ◽  
pp. 2993-2998 ◽  
Author(s):  
Sermet Koyuncu ◽  
Hsin-Wei Wang ◽  
Feng Liu ◽  
Kamil Bugra Toga ◽  
Weiyin Gu ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Band Gap ◽  
Organic Photovoltaics ◽  
Acceptor Pair ◽  
Low Band Gap ◽  
Donor Acceptor ◽  
Donor Acceptor Pair ◽  
Single Material

We report on the first synthesis of a highly crystalline donor–acceptor low band gap block copolymer by using diketopyrrolopyrrole (DPP) as a low band gap block and perylenebisimide (PDI) as a strong acceptor block.

Structural and Optical Characterization of CuxGaySe2Thin Films under Excitation with Above and Below Band Gap Laser Light

2002 ◽  
Vol 730 ◽  
Author(s):  
C. Xue ◽  
D. Papadimitriou ◽  
Y.S. Raptis ◽  
T. Riedle ◽  
N. Esser ◽  
...  
Keyword(s):  
Band Gap ◽  
Raman Spectra ◽  
Laser Light ◽  
Film Surface ◽  
Shallow Donor ◽  
Acceptor Pair ◽  
Donor And Acceptor ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

AbstractCuxGaySe2MOCVD and PVD grown films were structurally and optically characterized by Raman, Micro-Raman and photoluminescence spectroscopy. Defect related photoluminescence excitation with wavelengths varying across the material band gap reveals: a) in Cu-rich CuGaSe2films, three band edge splitting due to the spin-orbit interaction and the crystal field, and donor-acceptor pair recombination between a shallow donor and two different acceptor levels, and b) in Ga-rich CuGaSe2films, donor-acceptor pair transitions between quasi-continua of donor and acceptor levels related to potential fluctuations. Raman spectra of CuxGaySe2films, excited by laser light near and below the material band gap, show intense modes at 197cm-1, 187cm-1, and 277cm-1, which can be used as indicators of crystallinity and Ga-content of the films. Polarization- and angular- dependent micro-Raman spectra of MOCVD CuGaSe2indicate that CuxSey-crystallites, dispersed on the surface of Cu-rich films, are grown oriented with their c-axis perpendicular to the film surface.

A New Deep Acceptor in Epitaxial Cubic SiC

1989 ◽  
Vol 162 ◽  
Author(s):  
J. A. Freitas ◽  
S. G. Bishop
Keyword(s):  
Thin Films ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Excitation Intensity ◽  
Acceptor Pair ◽  
Deep Acceptor ◽  
Intensity Dependence ◽  
Pl Spectra ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

ABSTRACTThe temperature and excitation intensity dependence of photoluminescence (PL) spectra have been studied in thin films of SiC grown by chemical vapor deposition on Si (100) substrates. The low power PL spectra from all samples exhibited a donor-acceptor pair PL band which involves a previously undetected deep acceptor whose binding energy is approximately 470 meV. This deep acceptor is found in every sample studied independent of growth reactor, suggesting the possibility that this background acceptor is at least partially responsible for the high compensation observed in Hall effect studies of undoped films of cubic SiC.

scholarly journals Time-resolved Spectroscopy of the violet luminescence of undoped AlN

2005 ◽  
Vol 10 ◽  
Author(s):  
R. Freitag ◽  
K. Thonke ◽  
R. Sauer ◽  
D. G. Ebling ◽  
L. Steinke
Keyword(s):  
Epitaxial Layers ◽  
Yellow Luminescence ◽  
Acceptor Pair ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Violet Luminescence ◽  
Donor Acceptor ◽  
Violet Band ◽  
Donor Acceptor Pair

We report on the time-resolved luminescence of the defect-related violet band from undoped AlN epitaxial layers grown on sapphire and SiC. For both measurements in photoluminescence and in cathodoluminescence a decay of algebraic nature at long times is observed. This is typical for donor-acceptor pair transitions. We compare the behavior of this band to that of the generically yellow luminescence of GaN.

The role of potential fluctuations in continuous-wave donor–acceptor pair luminescence of heavily doped materials

1999 ◽  
Vol 75 (9) ◽  
pp. 1243-1245 ◽  
Author(s):  
I. Kuskovsky ◽  
D. Li ◽  
G. F. Neumark ◽  
V. N. Bondarev ◽  
P. V. Pikhitsa
Keyword(s):  
Continuous Wave ◽  
Acceptor Pair ◽  
Potential Fluctuations ◽  
Donor Acceptor ◽  
Heavily Doped ◽  
Donor Acceptor Pair ◽  
Doped Materials

Photoassociation due to electron transfer. Exciplex formation in non-polar solvent

1971 ◽  
Vol 24 (9) ◽  
pp. 1797 ◽  
Author(s):  
RJ McDonald ◽  
BK Selinger
Keyword(s):  
Polar Solvent ◽  
Excitation Energy Transfer ◽  
Acceptor Pair ◽  
Excitation Spectra ◽  
Fluorescence Excitation ◽  
Exciplex Formation ◽  
Reversible Dissociation ◽  
Fluorescence Excitation Spectra ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

Exciplexes may be formed by exciting either partner of a given electron donor-acceptor pair. As the formation of such exciplexes is reversible, dissociation may lead to excitation energy transfer. ��� The temperature dependence of fluorescence excitation spectra has proved to be a powerful tool for exploring these systems.

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