Lasing action in organic semiconductor thin films

Lasing action in optically pumped thin films of organic semiconductors has recently been demonstrated in a variety of materials employing a variety of cavity configurations. The excitation intensities required for lasing in optically pumped films are comparable to the electrical current densities achievable in light emitting devices based on these materials, opening the door to the possible realization of organic diode lasers. However, the design of diode laser structures is complicated by the relatively low charge carrier mobilities of organics. It has also been shown that the optical properties of organic films under electrical excitation are affected by the formation of polarons, imposing yet another obstacle for realization of these devices. The continuing research on organic diode lasers is motivated by the unique properties of these devices, such as narrow spectral emission linewidth and the temperature independence of laser output power and emission wavelength, which may be advantageous in a number of applications. (C) 1999 Elsevier Science Ltd. All rights reserved.