Low-frequency noise measurement and analysis in organic light-emitting diodes

Inst. of Mater. Res. & Eng., Singapore, Singapore
IEEE Electron Device Letters (Impact Factor: 2.75). 08/2006; 27(7):555 - 557. DOI: 10.1109/LED.2006.877283
Source: IEEE Xplore

ABSTRACT Low-frequency noise characteristics of organic light-emitting diodes are investigated. Two noise components were found in experimental low-frequency noise records, namely: 1) 1/f Gaussian noise from device bulk materials and 2) an excessive frequency-related part of noise related to device interfaces or defects and traps. 1/f noise is said to be related to carrier mobility. Degradation, especially photo-oxidation of the electroluminescence polymer, is a possible reason that affects carrier mobility. The excessive part of noise is believed to be related to the carrier numbers and could come from the interface deterioration, defects and traps generation and furnish. The excessive part of noise increases much faster during device stress. This shows that the degradation related interface defects and traps is much faster.

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Available from: Lin Ke, Mar 01, 2013
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    • "The correlation of LFN to material quality and device reliability has also made it a useful non-intrusive characterization tool [15] [16] [17] [18]. Recently, LFN studies have also been extended to non-traditional materials and devices, such as nanowire transistors [19] [20], graphene devices [21], organic light-emitting diodes [22], and organic thin-film transistors [23] [24]. However, there are few reports on the noise measurements of polymer solar cells. "
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    ABSTRACT: We investigate the dark low-frequency noise characteristics of P3HT:PCBM bulk heterojunction organic solar cells in both forward and reverse bias conditions. The current noise power spectral density (SI) is “1/f”-like and is compared among cells annealed at different temperatures (60 °C to 140 °C). The asymmetric relationship of SI versus DC dark current (IDC) can be explained by the competition between the recombination current noise and tunneling current noise. Among the different annealing temperatures, we find that higher annealing temperature yields smaller ratio of the Hooge parameter to the carrier recombination lifetime, which is reflected in the forward bias SI versus IDC relationship. We demonstrate that the low-frequency noise can serve as a non-destructive diagnostic indicator of the performance of organic solar cells.
    Solar Energy Materials and Solar Cells 11/2014; 130:151–155. DOI:10.1016/j.solmat.2014.07.009 · 5.34 Impact Factor
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    • "The interface deterioration has been proved to play an important role in the device degradation process [27], which definitely increases energy barrier fluctuations and causes fluctuations in the number of charge carriers [13]. The existence of high conductance fluctuations further suggests that a fraction of the OLED turns into a resistive switching layer due to internal modification. "
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    Noise and Fluctuations (ICNF), 2013 22nd International Conference on; 06/2013
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    ABSTRACT: Degradation induced changes in the structural and optical properties of polyfluorene-based light-emitting diodes are examined by using electroluminescence and low frequency noise (LFN) spectroscopic techniques. The materials studied are poly[2,7-(9,9′-dihexylfluorene)-alt-bithiophene] (P1) and poly[2,7-(9,9′-dihexylfluorene)-alt-thieno[3,2-b]thiophene] (P2). Improved emission spectra for a light-emitting device based on polymer P2 in terms of current efficiency, spectra stability, and lifetime are observed. A polymer P2-based device also presents long lifetime predicted by the smaller slope in the initial LFN spectra. Correlation of device LFN spectra with polymer structure change and lifetime is established. The increase in noise level predicts the undergoing degradation in bulk material and the increase in the noise slope predicts the fluctuation of carrier number and change in polymer structure. The redshift in emission spectrum for P2 after long-time driving is also picked up by the LFN spectrum.
    Journal of Applied Physics 09/2007; 102(6):063103-063103-4. DOI:10.1063/1.2778739 · 2.18 Impact Factor
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