Institut für Angewandte Photophysik (IAPP)

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1 Institut für Angewandte Photophysik (IAPP)

2 Professors working on organic semiconductors Chair for Optoelectronics Chair for Organic Photovoltaics Chair for Organic Semiconductors Karl Leo Physics Diploma Univ. Freiburg/Germany 1985 PhD Univ. Stuttgart 1988 AT&T Bell Labs Holmdel RWTH Aachen TU Dresden 1993 Co-founder of Novaled, Heliatek and 6 other spin-offs Koen Vandewal Photonics Engineering Univ. Ghent/Belgium 2004 PhD Univ. Hasselt/BE 2009 Univ. Linkoping/SE Stanford/USA TU Dresden 2014 Endowed Chair, Organic Photovoltaics Sebastian Reineke Physics Diploma TU Dresden/Germany 2005 PhD TU Dresden 2010 Postdoc MIT, Cambridge, Visiting Scientist LMU Munich TU Dresden 2014

3 Chair for Optoelectronics Prof. Karl Leo

4 Basic research on organics Studies of Transport and Doping in Organic Semiconductors Experiment and Modelling work closely together M. Tietze et al., Phys. Rev. B86, (2012)

5 Novel Transistor devices L B. Lüssem et al., Nature Comm. 4, 2775 (2013)

6 Organic Microlasers DBRs of 10.5 pairs TiO 2 /SiO 2 (R>99.9%) Reactive e-beam evaporation Active medium: organic small molecules (Alq 3 :DCM) Thermal co-evaporation k high Q-factors (>4000) low lasing threshold Easy control of the optical properties Confined light in z-direction discrete k z mode

7 Current possible Master Topics Leo group Optimized vertical transistors": The concept of vertical transistors offers various handles to adjust their working parameters and characteristics. These will be exploited to achieve improvements of the device performance. Efficient vertical organic light emitting transistors : Implementation and characterization of vertical device structures integrating a light emitting diode and its driving transistor. This device also enables the advanced characterization of the used vertical transistor." Silver Nanowires as Top Electrode for Small Molecule Solar Cells : The possibility of using silver Nanowires (AgNWs) as a top electrode for vacuum deposited small molecule solar cell will be explored. Techniques such as dry transfer or lamination will be studied as a possible way to transfer the AgNWs onto the solar cells.

8 Chair for Organic Photovoltaics Prof. Koen Vandewal

9 Organic solar cells Current record efficiency: 12 % Flexible Low cost Semitransparant Philips Building integration 8

10 Testing new materials in OPV devices Synthesis of new absorber materials by IAPP chemistry Power conversion efficiency (%) Small Molecule Polymer Year Thin film and device fabrication 9

11 Topics 1. New materials 2. Advanced light trapping Luminescent scatterers Light incoupling with flexible dielectric mirrors 3. Understanding and optimizing fundamental processes Charge carrier lifetimes Electro-luminesence 4. Organic NIR photodetectors Fast photodetectors shrinking dimensions + characterization Low noise photodetecors new device architectures + characterization 5. Device simulation Optical Electrical

12 Chair for Organic Semiconductors Jun.-Prof. Sebastian Reineke

13 OLED research Novel luminescent concepts

14 OLED research summarized

15 OLED outcoupling enhancement

16 Emitter development

17 Biluminescence Simultaneous emission from singlet and triplet states Singlet state Triplet state

18 Methods/skills we use 1. Material and device engineering Vacuum deposition and wet processing (spin coating) Lithography for structuring and complexity 2. Characterization of organic materials and devices (mostly luminescent properties) Electro-optical characterization of devices Continuous wave spectroscopy Time-resolved spectroscopy (future: temperature dependent) 3. Simulation Thin film optics (numerical; transfer matrix) Ray tracing Time dependent density functional theory (TD-DFT)

19 Where to find current and future topics? Or: Get in direct contact with the various groups.

20 Stefan C. B. Mannsfeld, Mike Hambsch Research at the Chair of Organic Devices Array of high-performance OFETs on a plastic film Underwater operation-capable OFETs

21 Advanced Processing of Organic Electronics Engineering the delivery of org. semiconductors for ultrahigh device performance Undesirable morphology Solution: No FLUENCE FLUENCE Printing direction 1cm 2 /Vs 11cm 2 /Vs Etch depth: 40μm 50mm 1mm Mannsfeld et al., Nature Mater. 12, (2013).

22 Organic Device Design - Sensors Organic field effect transistor with compressible dielectric Sensors for environmental, chemical and medical applications Roberts et al. PNAS 105, (2008) Mannsfeld et al., Nature Mater. 9, (2010)

23 Current Master Projects: Surface-Doping of OSC Literature: Surface doping of organic crystals and films with highly polar molecules Reversible surface doping of P3HT Calhoun et al. Nature Mater. 7, (2008) Topic 1: Development of robust, controllable surface doping method from solution. So far only demonstrated from vapor phase. Topic 2: Research towards novel OFET-based memory based on surface-doped channels. Use orthogonal lithography to structure surface doped regions Doped strip

24 Current Master Projects: Meltable OSC Fabrication of Semiconductor Films from Melts melt drawing, melt shearing of polymer semiconductor melts Low-melting point organic semiconductor: T M =80 C Adv. Func. Mater. 24, (2014) Colloid Polym Sci 267, (1989) nm