The ammonium dichromate acts as the photoactive site. Additional challenges involve the dispersion of CNT within the polymer photoactive layer. Photoresists have three major components, a solvent, resin, and sensitizer (or photoactive compound). The photographic paper base must be free of photoactive impurities such as iron and lignins. Benoxaprofen, since withdrawn due to its liver toxicity, was the most photoactive NSAID observed. To increase the photovoltaic efficiency, electron-accepting impurities must be added to the photoactive region. The photoactive layer can be created by mixing nanoparticles into a polymer matrix. The photoactive region of a CCD is, generally, an epitaxial layer of silicon. It is the only photoactive protein known to use a carotenoid as the photoresponsive chromophore. Photoactive yellow protein, PYP, is a blue-light sensor from the bacterium "H. halophila".