For organic light emitting diodes (OLEDs), it has advanced very quickly and already in market for lighting and display. The reliability and lifetime of those devices are acceptable.

The remaining problems may be the understanding of the device performance in the high current region. Under high field, several issues come out 1) Joule heat; 2) high current density; 3) roll-off; 4) conduction mechanism; 5) dynamic of excitons (singlets and triplets) and son on.

The first two issues can be solved by using high thermal conductivity substrate and at the same time using pulsed applied voltage to minimize the self-heating effects; on the other hand, for high current density, small electrode is expected. In contrast, the last three issues are still under study.

Recently, Prof. S. Forrest's reported the short-time scale time-revealed amplified stimulated emission (ASE), indicating that the lasing action lasted only for a short time interval below 100 ns due to the strong singlet triplet annihilation. The conclusions are further supported by other groups like Prof. T. Riedl' group.

On the other hand, to explain the larger external quantum efficiency (EQE), Prof. Leo and Prof. Friend are working on the triplet-triplet annihilation mechanisms, which indicated a 15% increase of EQE can be obtained via TTA. Although the motivations are little different, various studies come to same common point that are exciton dynamics in short time scale. Of course, the conduction mechanism is definitely an important issue, Prof. Blom is working on that point.

Electrically driven organic laser is a very interesting topic. However, considering the above experimental facts and various obstacles, what do you think about its future?