Application of barium strontium titanate (BST) as a light sensor on led lights

Barium Strontium Titanate (BST) film has been successfully produced
as a light sensor. The BST film was made by CSD method by reacting
barium acetate, strontium acetate and titanium isopropoxide with
mole fractions of 0.5; 0.5 and 1, respectively.The BST absorbance test
showed that BST film is sensitive to visible light ranging from 475 to
750 nm. The film test showed maximum absorbance at three peak
wavelengths, 475 nm, 593 nm, and 702 nm. The energy gap of the
BST film was 1.9 eV which showed that the film produced was a
semiconductor. The IV test showed that BST film is a photodiode.
This was indicated by the shift of the curve when tested in light and
dark conditions. The sensitivity test showed BST film is most sensitive
to blue light, signified by the most significant change in resistance.
The decrease in resistance of blue LED was 0.401KX/lux, while the
resistance decrease of green light was 0.051KX/lux and red was
0.288KX/lux. By using optical and electrical properties, BST thin film
could be used as light sensors to detect LED lights.