The relationship of current transfer ratio and input light wavelengths in the organic photocoupler

In this article we have fabricated an organic photocoupler with different wavelengths of organic light-emitting diodes as light source (input unit) and photodiode based on poly(3-hexylthiophene):1-(3-methoxycarbonyl)propyl-1-phenyl- (6,6)- C₆₁ as detector (output unit). The relationship between the current transfer ratio (CTR) and input light wavelengths was studied. The output current and CTR are increasing with the input light wavelengths decreasing from 624 to 470 nm, and the CTR value with 470 nm input wavelength is 3-12 times higher than that with other longer input wavelengths, indicating that the short wavelength input light generates photocurrent and CTR efficiently.