[Seminar] New molecular designs for organic gain materials, towards high-performance laser devices" by Dr. Robin Troiville-Cazilhac

The development of organic semiconductors has revolutionized optoelectronic devices, leading to inventions like organic light-emitting diodes (OLEDs) ^[1] and organic solar cells (OSCs) ^[2]. Organic materials offer several advantages over their inorganic counterparts, including ease of tuning properties and flexibility. Research is now increasingly focused on discovering new applications for these versatile materials. One major recent challenge has been developing organic semiconductor-based laser diodes ^[3]. These devices rely on an organic gain material to amplify light after electrical excitation. However, producing powerful and precise light from organic materials, which are inherently more fragile than inorganic materials, has proven to be a complex task.

 

A significant breakthrough came in 2019 with the demonstration of the first successful excitation of an organic gain material using electrical current injection ^[3]. This discovery fueled numerous studies, particularly those aimed at developing new organic gain materials. The primary goal for chemists is to synthesize compounds with the lowest possible laser thresholds, which translates to materials with a greater ability to amplify light.

 

This research involved the synthesis of several new gain materials, exploring three categories: alternating copolymers incorporating electron donor-acceptor units, molecular liquid crystals, and polymers with fluorescent liquid crystal units attached to their side chains. Following organic synthesis, a multidisciplinary approach was employed, encompassing the optical and structural characterization of these materials, culminating in light amplification tests. Ultimately, the materials with the most promising results were integrated into functional lasing devices.

 

This presentation will discuss the advantages and disadvantages of these three material types, along with the molecular engineering techniques used to improve their light amplification properties. Finally, all the light amplification results and the resulting lasing devices will be presented for comparison of these different strategies.

[1] H. Uoyama, K. Goushi, K. Shizu, H. Nomura, and C. Adachi, Nature, 2012, 492, 234-238.

[2] Y. Liu, J. Zhao, Z. Li, C. Mu, W. Ma, H. Hu, K. Jiang, H. Lin, H. Ade, H. Yan, Nat Commun 2014, 5, 5293.

[3] A. S. D. Sandanayaka, T. Matsushima, F. Bencheikh, S. Terakawa, W. J. Potscavage, C. Qin, T. Fujihara, K. Goushi, J.-C. Ribierre, C. Adachi, Appl. Phys. Express 2019, 12, 061010.