Revolutionize Building (Mob Repellant/Preventer)

The idea is not to change lighting, or have invisible lighting like some others have suggested, but what if there was a substance that could be placed to prevent the spawning and attraction of mobs? It would be invisible and would allow for builds in survival to be so much cooler, without having to be fully lit or carpeted. It could be crafted from a farmable item, I'm thinking rotten flesh (finally, a use for it) that is mixed with sugar (to create a paste), and thus a player would have mob repellant. Now, cool nighttime cities and so many other things can be made without mobs spawning in to ruin the effect.