Reporting their findings in the journal Applied Physics Express under the title “Indication of current-injection lasing from an organic semiconductor”, the researchers circumvented the traditional issues of organic materials (which due to their inherent resistance, tend to break down under the high currents required for lasing).
A critical step in lasing is the injection of a large amount of electrical current into the organic layers to achieve a condition called population inversion. However, the high resistance to electricity of many organic materials makes it difficult to get enough electrical charges in the materials before they heat up and burn out. On top of that, a variety of loss processes inherent to most organic materials and devices operating under high currents lowers efficiency, pushing the necessary current up even higher.
To overcome these obstacles, the research group led by Prof. Chihaya Adachi used a highly efficient organic light-emitting material, 4,4'-bis[(N-carbazole)styryl]biphenyl (BSBCz) with a relatively low resistance to electricity and a low amount of losses—even when injected with large amounts of electricity.