Organic photochromic compounds offer great potential for advancing light-controlled electronics1-3. Their ability to reversibly change properties such as absorption, photoluminescence, and redox potentials under light makes them suitable for various photonic applications2. To date, research on photochromic molecules concentrated on their switching properties in solution or single-crystal forms, thus limiting their use in thin-film devices4. Recently, it has been shown by our group that main-chain photochromic polymers can form thin-films that reversibly switch in the solid-state and efforts are now focussed on improving the speed of cyclisation and reverse cyclisation5. this project is therefore based on investigating how the molecular architecture and their corresponding free volume affects the photoswitching properties of photochromic materials in the solid state. In particular, the effect of plasticizers on photoswitching behavior is examined.