Defects in porous silicon investigated by optically detected and by electron paramagnetic resonance techniques

1993 ◽  
Vol 63 (15) ◽  
pp. 2120-2122 ◽  
Author(s):  
B. K. Meyer ◽  
D. M. Hofmann ◽  
W. Stadler ◽  
V. Petrova‐Koch ◽  
F. Koch ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Porous Silicon ◽  
Paramagnetic Resonance ◽  
Optically Detected ◽  
Electron Paramagnetic

Electrically and Optically Detected Electron Paramagnetic Resonance in Blue Organic Light Emitting Diodes

2021 ◽  
Author(s):  
◽  
Rebecca Jane Sutton
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Great Promise ◽  
Paramagnetic Resonance ◽  
Light Emitting ◽  
Emissive Layer ◽  
Organic Light ◽  
Optically Detected ◽  
Electron Paramagnetic

<p>Organic light emitting diodes (OLEDs) are an emerging technology based on electrically conducting polymer films, with great promise for large area lighting and flexible ultra-thin displays. However, despite the rapid technological development, there is still a poor understanding of the degradation and spindependent recombination processes that take place inside an OLED. In this thesis, Electron Paramagnetic Resonance (EPR) was used to investigate these processes in blue-emitting OLEDs.  A successful procedure was developed and refined for fabricating OLEDs with the structure ITO/PEDOT:PSS/emissive layer/Al/Ag, with and without the PEDOT:PSS hole-transporting layer. The organic emissive layer was either F8BT, PFO, or PVK:OXD-7:FIrpic (PB). These OLEDs were fabricated in air and with a geometry optimised for EPR experiments. Critical features for satisfactory devices were found to be a sufficiently thick organic layer and minimal exposure to the air.  A compact apparatus was developed for simultaneous light output, current, and voltage measurements on the OLEDs while in an inert glove box environment. Electroluminescence and current-voltage parameters measured for these devices showed predominantly trap-controlled space-charge-limited conduction.   OLEDs with PFO as the emissive layer and with a PEDOT:PSS layer were investigated with conventional, electrically-detected (ED) and optically-detected (OD) EPR techniques. EDEPR and ODEPR signals were observed at ~9.2 GHz and in the low (<50 mT) and high (~330 mT) magnetic field regimes and were found to change markedly with time during operation as the device degraded. The low field signals initially showed a composite broad quenching and superimposed narrow enhancing response centred around zero field strength. These signals were attributed to magneto-resistance (MR) and magneto-electroluminescence (MEL). Following operational ageing, a third, narrow quenching line was observed in the MR and the ratio of the initial two MR responses changed substantially. These effects are tentatively attributed to a hyperfine interaction.  For both EDEPR and ODEPR, quenching high field resonances with a g-value (gyromagnetic ratio) of 2.003±0.001 were observed. The current-quenching resonance gradually diminished during operation and after 4–5 hours was replaced by a current-enhancing resonance. The appearance of this latter resonance could be explained by chemical changes in the OLED due to the diffusion of oxygen through the device from the oxygen-plasma-treated ITO. A working model is proposed which can explain this observed change as spindependent trapping and recombination at free radicals, although the model requires further experimentation to test its validity.</p>

Electron paramagnetic resonance study of luminescent stain etched porous silicon

1995 ◽  
Vol 66 (26) ◽  
pp. 3660-3662 ◽  
Author(s):  
M. Schoisswohl ◽  
J. L. Cantin ◽  
H. J. von Bardeleben ◽  
G. Amato
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Porous Silicon ◽  
Electron Paramagnetic Resonance Study ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

Spectroscopy of Proton Implanted GaN

1998 ◽  
Vol 537 ◽  
Author(s):  
M.G. Weinstein ◽  
M. Stavola ◽  
C.Y. Song ◽  
C. Bozdog ◽  
H. Przbylinska ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Vibrational Spectroscopy ◽  
Paramagnetic Resonance ◽  
Tentative Assignment ◽  
Vibrational Bands ◽  
Si Doped ◽  
Proton Implantation ◽  
Optically Detected ◽  
Electron Paramagnetic

AbstractVibrational spectroscopy, photoluminescence, and optically detected electron paramagnetic resonance (ODEPR) have been used to characterize the defects produced in undoped and Si-doped GaN by the implantation of hydrogen. Several new vibrational bands were found near 3100 cm-1 in GaN that had been implanted with protons. These frequencies are close to those predicted for VGa-Hn complexes, leading to the tentative assignment of the new lines to VGa defects decorated with different numbers of H atoms. The proton implantation also produces an infrared PL band centered at 0.95 eV and the ODEPR spectrum labeled LEI, both of which were seen previously for electron-irradiated GaN.

Observation of (100) surfaces in p-type porous silicon by electron paramagnetic resonance

1996 ◽  
Vol 276 (1-2) ◽  
pp. 241-243 ◽  
Author(s):  
J.L Cantin ◽  
M Schoisswohl ◽  
H.J von Bardeleben ◽  
N.Hadj Zoubir ◽  
M Vergnat
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Porous Silicon ◽  
Paramagnetic Resonance ◽  
P Type ◽  
Electron Paramagnetic

Electron paramagnetic resonance study of porous silicon

1992 ◽  
Vol 60 (17) ◽  
pp. 2116-2117 ◽  
Author(s):  
S. V. Bhat ◽  
K. Jayaram ◽  
D. Victor S. Muthu ◽  
A. K. Sood
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Porous Silicon ◽  
Electron Paramagnetic Resonance Study ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic
Sign in / Sign up

Export Citation Format

Share Document