We use e-beam lithography to pattern an indium tin oxide (ITO) electrode to create arrays of conjugated-polymer LEDs, each of which has a hole-injecting contact limited to 100 nm in diameter. Using optical microscopy, we estimate that the electroluminescence from a 100 nm diameter LED comes from a region characterized by a diameter of approximately 170 nm. This apparent broadening occurs due to current spreading within a PEDOT:PSS layer which was included to aid hole injection.

The authors report the first direct detection of x-ray induced photocurrents in thick films ͑up to 20 m͒ of conjugated polymers. Schottky-based "sandwich" structures were fabricated from layers of either poly͓1-methoxy-4-͑2-ethylhexyloxy͒-phenylenevinylene͔ ͑MEH-PPV͒ or poly͑9,9-dioctylfluorene͒ ͑PFO͒ on indium tin oxide substrates using a top contact of aluminum. Good rectification was achieved from the Al-polymer contact, with a reverse bias leakage current density as low as 4 nA/ cm 2 at an electric field strength of 25 kV/ cm. Irradiation with x-rays from a 50 kV x-ray tube produced a linear increase in photocurrent over a dose rate range from 4 to 18 mGy/ s. The observed x-ray sensitivities of 240 nC/ mGy/ cm 3 for MEH-PPV and 480 nC/ mGy/ cm 3 for PFO structures are comparable to that reported for Si devices. A response time of Ͻ150 ms to pulsed x-ray irradiation was measured with no evidence of long-lived current transients. Conjugated polymers offer the advantage of easy coatability over large areas and on curved surfaces. Their low average atomic number provides tissue-equivalent dosimetric response, with many potential applications including medical x-ray and synchrotron photon detection.

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