| AVS 55th International Symposium & Exhibition | |
| Electronic Materials and Processing | Thursday Sessions |
| Session EM-ThA |
| Session: | Organic Electronics |
| Presenter: | J.E. Royer, University of California, San Diego |
| Authors: | J.E. Royer, University of California, San Diego J. Park, University of California, San Diego C.N. Colesniuc, University of California, San Diego F. Bohrer, University of California, San Diego A. Sharoni, University of California, San Diego I.K. Schuller, University of California, San Diego W.C. Trogler, University of California, San Diego A.C. Kummel, University of California, San Diego |
| Correspondent: | Click to Email |
A systematic approach to isolating the cause of device degradation (“aging”) in copper phthalocyanine (CuPc) organic thin film transistors (OTFTs) is presented. Aging is one of the primary impediments to the widespread deployments of OTFTs in gas sensors and as drivers for OLEDs. Exposure of 1000ML thick CuPc OTFTs to a sequence of environments including ambient air, clean dry air (20% O2/N2), water vapor and N2 isolated the causes of device degradation in thick CuPc OTFTs. Initial exposure to ambient air increases conductivity of the CuPc film but also causes rapid device aging characterized by increased threshold voltage and loss of saturation behavior consistent with a loss of control of the channel conductivity by the gate. Exposure of the thick CuPc OTFTs to clean dry air, H2O/N2 mixture, or clean air/H2O mixture not only prevents aging but can counter the aging effect of ambient air. This suggests that O2, H2O and O2/H2O products are not responsible for the aging process in ambient air. The data is consistent with trace strong oxidants in ambient air (e.g. O3 and NOx) being responsible for OTFT aging via formation of fixed charge. The aging effect is only present in thick films and is attributed to strong oxidants dissociative chemisorbing in grain boundaries to form fixed charges which degrade the control of the OTFT conductivity by the gate.