Continuing Progress and the Latest Breakthroughs in the Field of Organic Optoelectronics

Organic electronics and optoelectronics (OE) are fast developing branches of modern science and technology that are aiming to compliment conventional inorganic semiconductors with light, inexpensive, and flexible organic materials. A traditional approach in OE is to build the very same device architecture and optimize different parameters in order to obtain the highest device performance. Practically, this approach proved to be very effective; however, it lacks scientific challenges and thus, obtained fundamental knowledge is marginal. When conceptually a new idea is introduced into device’s design, truly novel information can be revealed about mechanisms of device operation resulting in achieving a performance breakthrough. This can be done by using either one or a combination of following strategies: i) new engineering technology for device fabrication, ii) new type of devices, iii) utilization of a new class of materials. In my talk, I am going to show how those strategies facilitate recent progress in the field of OE.

In particular, I will describe recently discovered inversion mode organic thin film transistors enabled by molecular doping technology. Another great example of enabling technology is organic friendly orthogonal photolithography technology, which allowed building of e.g. high-voltage organic solar cells, OTFT based circuits and RGB OLED displays.

New device architecture creates a new platform to study the property of materials and interfaces. Organic semiconductor microcavities (OMC) e.g. can confine the light on a nano scale and provide a laboratory for semiconductor quantum optics and photonics. Strongly localized Frenkel excitons in organic semiconductors exhibit a much higher binding energy and oscillator strength than the Wannier-Mott excitons found in inorganic semiconductors. In addition, virtually unlimited material design possibilities and low re-absorption due to large Stokes shifts make OMC attractive for studying linear and non-linear optical effects. In our recent work, we experimentally demonstrated that proper design of metal electrodes inside the OMC doesn’t negatively affect the lasing threshold.

Finally, recently employed new class of materials organic-inorganic halide perovskites made a revolution in thin film solar cells. CH3NH3PbX3 (X = Cl, Br, or I) perovskites made a rapid progress in power conversion efficiency from 3.8% in 2009 up to more than 15% in 2013. I will make a quick review on that topic and try to explain why this particular class of materials outperforms organic solar cells and what are the challenges facing practical application.