Photoluminescence and Raman spectroscopy studies of the photodegradation of poly(3-octylthiophene)

Abstract

International audienceThis work examines the photodegradation of poly(3-octylthiophene) (P3OT) by UV-irradiation at 405 nm under vacuum and as a function of temperature (300 and 10 K). Two different P3OT films were studied. The first one was electrochemically synthesized on platinum plate and chemically reduced in a basic medium (P3OT-E) whereas the second one, chemically synthesized was spread out on glass by casting process from polymer previously dissolved in chloroform (P3OT-Q). After 200 s under UV illumination, the photoluminescence (PL) spectra observed on the P3OT-E samples showed an unexpected increase of some eight times in the emission intensity. In contrast, the PL spectra of P3OT-Q, subjected to the same temperature, pressure and photoirradiation time, showed a drop of to around half the initial signal intensity. Similarly experiments were performed at low temperature 10 K. In this temperature condition, PL spectra of P3OT-E and P3OT-Q obtained under photoirradiation, presented similar decreases of the intensity of their fluorescence. In order to explain these different results, Raman spectroscopy studies had been performed, and it was been possible to follow the formation of C=O group on the side alkyl chain after 200 min of irradiation. From the results obtained, we proposed a mechanism to explain the unexpected intensification of the PL emission signal for P3OT-E at 300 K. This mechanism was based on the destabilization of the charge transfer complex between the radical cations in P3OT-E and the residual dioxygen

Environmental effects of ozone depletion and its interactions with climate change: progress report, 2015

“…However, improving their durability to ensure a long service life (>20 years) is critical for their commercialisation. The mechanisms of photodegradation have been studied for the light-sensitive polymers in organic PV cells [363][364][365] as well as their plastic encapsulants. [366][367][368] In a recent report, residual additives left in the light-sensitive polymer during manufacturing, which are confined and sandwiched between plastic laminates, were shown to promote accelerated degradation of these polymers.…”

Photodegradation of C‐PCPDTBT and Si‐PCPDTBT: Influence of the Bridging Atom on the Stability of a Low‐Band‐Gap Polymer for Solar Cell Application

“…[8][9][10] For the state-of-the-art polymer poly(3-hexylthiophene) (P3HT) and related blends, the degradation mechanism and the influence of several environmental conditions are still dis-cussed intensely. [6,[11][12][13][14][15][16][17][18] However, the detailed degradation mechanism depends on the considered polymer (or blend) [19,20] and a detailed understanding is necessary for future developments.…”

Complex Photobleaching Behavior of Semiconducting Polymer Dots

“…Poly(fluorene) polymers degrade in the presence of oxygen to form keto (9-fluorenone) defect sites, with a possible carboxyl defect as an intermediate. 66,67 Photodegradation of CPs is also known to occur in the absence of oxygen, including for F8BT, 68,69 other poly-(fluorenes), 70 PH3T, 71 other thiophenes, 72 and PPV-type polymers. 73 In general, the degradation has been attributed to cross-linking and other reactions involving radicals (e.g., chain scissions, Norrish, photo-Fries).…”

“…Photodegradation of CPs is also known to occur in the absence of oxygen, including for F8BT, , other poly­(fluorenes), PH3T, other thiophenes, and PPV-type polymers . In general, the degradation has been attributed to cross-linking and other reactions involving radicals (e.g., chain scissions, Norrish, photo-Fries). , For a PPV-type polymer, an out-of-cage reaction is thought to occur with loss of conjugation, and this reaction is in competition with a photo-Fries reaction that yields hydroxyl groups on the polymer .…”