Photonic devices made with semiconducting conjugated polymers: New developments

We present recent progress on polymer devices developed at UCSB. We have fabricated polymer devices with dual functions: light emission and photodetection. The same Ca/MEH-PPV/ITO devices can be used as light emitting devices under forward bias with external quantum efficiency of ∼1% photons/electron, and as photodiodes under reverse bias with photosensitivity of −90mA/Watt and quantum yield of −20% electrons/photon (∼ 1μW/cm2, 430nm). We have also fabricated polymer photodiodes with P3OT and MEH-PPV:C60 composites with excellent visible-UV sensitivity. For wavelengths shorter than 540 nm, the sensitivity is over 0.3A/Watt under reverse bias of 15 V, greater even than that of commercial UV-enhanced Si photodiodes. By matching MEH-PPV LEDs with P3OT photodiodes, we have demonstrated polymer optocouples with current transfer rate of ∼2×10−3, comparable to that of commercial optocouplers made with inorganic semiconductors.