{"title":"Charge Carrier Dynamics in Pulse-Irradiated Polyphenylenevinylenes: Effects of Broken Conjugation, Temperature, and Accumulated Dose","authors":"Gerwin H. Gelinck, John M. Warman","doi":"10.1021/jp962051h","DOIUrl":null,"url":null,"abstract":"<p >The transient conductivity resulting from nanosecond pulsed ionization of alkoxy-substituted phenylene?vinylene/ethylidene copolymers, “dMOM-PPV(<i>n</i>)”, with <i>n</i> the fractional vinylene content, has been studied using the pulse radiolysis time-resolved microwave conductivity (PR-TRMC) technique. Minimum values of the sum of the charge carrier mobilities within the bulk solids, ∑μ<sub>min</sub>, have been estimated from the end-of-pulse conductivity. For the freshly precipitated materials at room temperature, ∑μ<sub>min</sub> decreases gradually with decreasing <i>n</i> from 1.8 × 10<sup>-7</sup> m<sup>2</sup>/(V s) for <i>n</i> = 1 (full conjugation) to 0.4 × 10<sup>-7</sup> m<sup>2</sup>/(V s) for <i>n</i> = 0.57. After annealing dMOM-PPV(1) at 100 and 150 °C, ∑μ<sub>min</sub> at room temperature increased to 3.2 × 10<sup>-7</sup> and 8.0 × 10<sup>-7</sup> m<sup>2</sup>/(V s), respectively. No significant effect of high-temperature annealing was found for <i>n</i> ≤ 0.87. On cooling dMOM-PPV(1) from 150 to ?50 °C, ∑μ<sub>min</sub> decreased initially with an activation energy of approximately 0.07 eV but approached a plateau at the lowest temperatures. The after-pulse decay of the conductivity was disperse in all cases. First half-lives of several microseconds were found for <i>n</i> = 1. The decay kinetics were independent of the dose in the pulse. Large accumulated radiation doses (up to 1.2 MJ/kg) did not effect the end-of-pulse conductivity but did increase the decay rate. This effect could be reversed by high-temperature annealing. </p>","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.7810,"publicationDate":"1996-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1021/jp962051h","citationCount":"25","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Journal of Physical Chemistry ","FirstCategoryId":"1","ListUrlMain":"https://pubs.acs.org/doi/10.1021/jp962051h","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 25
Abstract
The transient conductivity resulting from nanosecond pulsed ionization of alkoxy-substituted phenylene?vinylene/ethylidene copolymers, “dMOM-PPV(n)”, with n the fractional vinylene content, has been studied using the pulse radiolysis time-resolved microwave conductivity (PR-TRMC) technique. Minimum values of the sum of the charge carrier mobilities within the bulk solids, ∑μmin, have been estimated from the end-of-pulse conductivity. For the freshly precipitated materials at room temperature, ∑μmin decreases gradually with decreasing n from 1.8 × 10-7 m2/(V s) for n = 1 (full conjugation) to 0.4 × 10-7 m2/(V s) for n = 0.57. After annealing dMOM-PPV(1) at 100 and 150 °C, ∑μmin at room temperature increased to 3.2 × 10-7 and 8.0 × 10-7 m2/(V s), respectively. No significant effect of high-temperature annealing was found for n ≤ 0.87. On cooling dMOM-PPV(1) from 150 to ?50 °C, ∑μmin decreased initially with an activation energy of approximately 0.07 eV but approached a plateau at the lowest temperatures. The after-pulse decay of the conductivity was disperse in all cases. First half-lives of several microseconds were found for n = 1. The decay kinetics were independent of the dose in the pulse. Large accumulated radiation doses (up to 1.2 MJ/kg) did not effect the end-of-pulse conductivity but did increase the decay rate. This effect could be reversed by high-temperature annealing.