Abstract: 

The brilliant color reflected from nature stems from a photonic crystal morphology.  There are many examples in biology of the manipulation of sunlight by nanoscale features including such diverse applications as temperature control, mate attraction, antireflection, and the efficient collection of low light levels.  In particular, the striking “structural black” —an absence of reflected visible light—of butterfly scales suggests that biomimicry might be a viable route to enhanced optolectronic devices. Here we describe a materials-agnostic, 2-D, photonic crystal morphology that enhances the efficiency of optoelectronic devices.  The morphology is developed by patterning the organic photoactive material via fluorine chemistry, a method that lends itself to large area fabrication of photonic crystal nanostructures. The photonic crystal cell morphology increases photocurrents generally, and particularly through the excitation of resonant modes near the band edge of the organic photovoltaic material. The device performance of the photonic crystal cell showed a nearly doubled increase in efficiency relative to conventional planar cell designs.[1] The nanopattern structure as a form of  waveguide can also enhance performance of other devices including an a smart window[2], an organic laser[3], a battery[4]. Also the structure is showing a promising way to harness the entire solar spectrum by converting both ultraviolet and near-infrared to visible light concurrently through resonant-mode excitation.[5]

References

[1] Photonic crystal geometry for organic solar cells Ko, D.-H.; Samulski, E. T. et al. Nano Lett. 2009, 9, 2742

[2] Optically Switchable Smart Windows with Integrated Photovoltaic Devices’ H.K Kwon, Ko, D.-H* et al Adv. Energy Mater. 2015, 5, 1401347

[3] Additive-Free Hollow-Structured Co3O4 Nanoparticle Li-Ion Battery: The Origins of Irreversible Capacity Loss” Cho,S.E., Ko, D.-H.*; Park B.N* et al. ACS Nano. 2014,  8, 6701

[4] Blue-phase templated fabrication of three-dimensional nanostructures for photonic applications” Castles, F.; Day, F. V.; Morris, S. M.; Ko, D.-H, Friend, R.; Coles,  H. J.* et al.  Nature Mater. 2012, 11, 599

[5] Simultaneous Enhancement of Upconversion and Downshifting Luminescence by Plasmonic structure” Lee, K.T.; Ko, D.-H* et al. Nano letters, 2015, Article ASAP DOI: 10.1021/nl5049803

2015년 4월 9일(목) 고두현교수 세미나 표지.hwp