The electroluminescent and photodiode device made of a polymer blend

Organic thin film diodes made by a polymer blend of poly[2-methoxy,5-(2ʹ-ethyl-hexoxy)-1.4-phenylenevinylene] (MEH-PPV) and poly[1.3-propanedioxy-1.4-phenylene-1,2-ethenylene-(2.5-bis(trimethylsilyl)-1,4-phenylene)-1,2-ethenylene-1,4-phenylene] (called the B-polymer) are investigated. The device of sandwich configuration indium-tin oxide (ITO)/polymer-blend/A1 emits orange light under forward bias at + 10 V and the same device acts as a photodiode under reverse bias. To investigate the photodiode characteristics, the 516 nm wavelength with 9.5 mW/cm2 intensity of light is illuminated through the A1 contact side of the device. The I-V characteristic measurement shows the short circuit current and the open circuit voltage of −1.22 × 10−9 A/cm2 and 0.8 V, respectively. The ratio of the photocurrent to the dark current is about 4 × 102 at − 2.5 V reverse bias. The maximum d.c. sensitivity is 1.35 × 10 −5 A/W at 4× 7 V reverse bias voltage with 16 mW/cm2 intensity of the incident light. The results indicate the possibility of making photosensors using this device.