When The semiconductor product is translucent, the light will be emitted from the junction as junction acts given that the source of gentle. LED is operated in ahead biased mode only. If it will eventually run in reverse biased it can get harm since it can't with stand reverse voltage. https://www.uk-exhibitionstands.co.uk/product/air-inflatable-backlit-square-tower-3m-3200mm-h-2/