Efficient white light emission in conjugated polymer homojunctions

Abstract

We study polymer light-emitting diodes with a homojunction, i.e., junction between two layers with the same host material. One layer is poly (9,9-dioctylfluorene-2,7-diyl) (PFO) host blended with a small amount of poly (2-methoxy-5 (2'-ethyl-hexyloxy)-1,4-phenylene vinylene), another layer is either pure PFO or PFO host blended with green-emitting polyfluorene copolymers. Such homojunction devices are solution processed and show efficient white light emission. The peak luminance 3000cd∕m2 is reached at 10V with Internationale de L’Eclairage (CIE) coordinate (0.34, 0.34).

Effect of the polymer emission on the electroluminescence characteristics of n-ZnO nanorods/p-polymer hybrid light emitting diode

“…These LEDs utilize the advantageous of both the n-ZnO and the p-type polymers. All three LEDs have shown diode behavior and the ideality factors were very close to each other 15 implying that almost identical electrical properties. Nevertheless the quality of the combined optical emission of the ZnO and the p-type polymer from the three LEDs was quite different.…”

“…Blended polymer solutions have been used in OLEDs for a long time. By blending the polymers, the photoluminescence efficiency can be increased and the charge transport properties can also be enhanced [13,14,15]. Blending polymer is also useful to tune the emitted colour and to control the electrical properties [16,17].…”

Polyfluorene based blends for white light emission

“…This energy transfer has to be incomplete, since all the colors should appear in the electroluminescence spectrum, requiring a judicious control in the concentration balance and miscibility of the mixture materials [14,15]. The basic operating mechanism involves the charge carriers injection, a partial energy transfer in order to avoid cascade non-radiative decays that will lead only to the lower-laying emission from the excited state [16,17].…”

Dipolar alignment and consequent enhanced charge transport in poly (9, 9′ di octyl fluorene)-2, 7-ylene ethylnylene

“…Poly p-phenylenevinylene and its derivatives are the most significant materials for the fabrication of polymer light-emitting diodes and polymer photovoltaic devices due to their maximum absorbance and good photoluminescence in nature. [1][2][3][4][5] Presently, poly (9,9 0 dioctylfluorene) (PFO) is the most intensively investigated polymeric material for the lightemitting device applications due to very high hole mobility m h %10 À4 -10 À3 cm 2 /V s, and in many cases these show nondispersive hole transport at room temperature. [6][7][8] The performance of these devices depends primarily on the electrical conduction property of the polymers.…”