Control of cationic conjugated polymer performance in light emitting diodes by choice of counterion |
| |
Authors: | Yang Renqiang Wu Hongbin Cao Yong Bazan Guillermo C |
| |
Institution: | Mitsubishi Chemical Center for Advanced Materials, Department of Materials, Institute for Polymers and Organic Solids, University of California, Santa Barbara, California 93106, USA. |
| |
Abstract: | Counterion exchange in cationic conjugated polyelectrolytes provides for a straightforward method to modulate the performance of these materials as the electron transport (injection) layer (ETL) in organic light emitting diodes. The bromide counterions of (9,9-bis(6'-N,N,N-trimethylammonium)-hexyl)fluorene]bromide (PF-Br) can be easily replaced with trifluoromethylsulfonate (PF-CF3SO3), tetrakis(imidazolyl)borate (PF-BIm4) or tetrakis(3,5-trifluoromethylphenyl)borate (PF-BArF4) by a procedure that involves precipitation and washing. The performance of LEDs using MEH-PPV as the emissive layer, Al as the cathode, and the conjugated polyelectrolytes as the ETL varies in the order: PF-BIm4 > PF-CF3SO3 > PF-Br > PF-BArF4. In the case of PF-BIm4, the luminous efficiencies of the devices are similar to those of devices using Ba as the cathode. Thus, by properly choosing the counterion one can use higher work function metals that are more stable than lower work function metals without a substantial barrier to electron injection. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|