Cantilevers with integrated organic LEDs for scanning probe microscopy

Abstract

Organic thin films which are based on Van der Waals-bonded molecular organic compounds can be deposited onto a variety of substrates including scanning probe cantilevers without the lattice-matching constraints of conventional covalently-bonded semiconductors. Here we demonstrate organic light-emitting devices (OLEDs) fabricated on scanning probe cantilevers using thermal evaporation of molecular organic compounds and metallic electrodes. Ion beam lithography was used to define the emissive region in the shape of a ring having a diameter of 5 micrometers. The width of the ring emission was less than a micron as measured in the far field. Stable light emission was observed from the device at forward bias, with a current-voltage response similar to that of archetypal OLEDs. Such a probe can enable a new form of electrically-pumped SNOM compatible with existing atomic force microscopy tools and techniques. The emission wavelength can be tuned across the entire visible spectrum, including white light emission, by altering the composition of the emissive layer with a wide range of luminescent dyes. Should the ring-shaped light emission be used for imaging, the sample image can be deconvolved using a ring filter to achieve high resolution. The OLED probe can also be used to transfer excitons through the cathode to a sample via plasmon-assisted energy transfer; such a probe would be valuable for studying exciton dynamics in organic or organic/inorganic hybrid photovoltaic devices. By demonstrating the first active organic device on a scanning probe cantilever, this work opens the door to a wide range of new scanning probe techniques based on this class of materials for areas such as biological imaging.

Report on 6th U.S.–Japan Joint Seminar on Nanoscale Transport Phenomena—Science and Engineering

“…Pipe [62] presented a new optical probe enabling highly resolved optical imaging beyond the diffraction limit of light. The novel probe consists of a photodiode and organic LEDs monolithically integrated on the tip of a scanning probe.…”