Degradation of MEH-PPV due to Oxygen/Moisture Traps through C-V Analysis and Attenuated Total Reflection IR Spectroscopy

Abstract

We present the studying of oxygen and moisture traps in MEH-PPV through the MIS Capacitance – Voltage (C-V) analysis, and the Attenuated Total Reflection Infrared (ATR IR) spectroscopy technique. The presence of oxygen studied by ATR IR has also been verified by optical images from high resolution optical microscope. In quasi-static C-V measurements of the MIS (Al/MEH-PPV/p-Si) capacitors made, an extension of the weak inversion region was measured before strong inversion, which becomes more pronounced with aging. This increase in the weak inversion region is attributed to electron trapping by oxygen to form negative ions in the MEH-PPV layer. ATR IR spectroscopy shows the formation of carbonyl peak at 1651 cm−1 with aging, which is due to the presence of oxygen. Both the C-V analysis and Attenuated Total Reflection IR Spectroscopy are powerful tools for investigating the degradation of MEH-PPV polymer.

Exciton Dynamics of MEH‐PPV polymer based Nanocomposites: Effect of Molecular Orbital Energy Levels of Nanoparticles**

“…Both MEH-PPV and HyNCs exhibited a similar degradation mecha- ChemistrySelect nism with carbonyl group formation (CÀ O) at 1700 cm À 1 due to an attack of oxygen, [38] OÀ H bond formation owing to the moisture intervention and distortion of the phenyl group signifying the disintegration of the long conjugated segments due to the combined effect of light and oxygen. [37,40] However, the carbonyl formation in Zn PPV and Zr PPV occurred only after 3 weeks and 6 weeks of exposure respectively, whereas pristine MEH-PPV films started to degrade rapidly within 1 week of exposure. Thus, the incorporation of metal oxide NPs has prevented the attack of oxygen thereby lowering the degradation rate.…”

High Performance Color Conversion Polymer Films and Their Application to OLED Devices

“…However, once the films had been dried, air exposure significantly degraded the PL eff . Moisture and oxygen adversely affect the characteristics of MEH-PPV derivatives [16][17][18]. Moisture and oxygen on the non-dried films had trouble diffusing and penetrating the films due to the presence of residual solvent.…”

Single-Molecule Spectroscopy Reveals the Conformational Heterogeneity of Conducting Polymers Encapsulated within Hollow Silica Spheres

“…Poly- para -phenylenevinylene (PPV) and its derivatives are among the most important conducting polymers due to their potential use in organic transistors and in electroluminescence devices. , However, in spite of the interesting properties of these compounds and their applicability to develop technology at the nanometer scale, they suffer from a poor stability due to the lability of the CC bonds that tend to undergo oxidative degradation. − …”

“…1,2 However, in spite of the interesting properties of these compounds and their applicability to develop technology at the nanometer scale, they suffer from a poor stability due to the lability of the CdC bonds that tend to undergo oxidative degradation. [3][4][5] Encapsulation within porous inorganic matrixes can be a viable methodology to enhance the stability of an organic molecule, particularly when there is a tight fit between the incorporated guest and the inert walls of the host. 6 In addition, preparation of polymers inside micro-/mesoporous inorganic matrixes has attracted interest due to the remarkable properties of the intimate composite material resulting from the encapsulation.…”