This mod adds infinite research for the characters logistic request slots.

Each tier adds another 6 slots.

The pricing model is a linear one. Each tier costs 1000 science more (2000, 3000, 4000, ... ). Space science packs are not required.

If you think this is too cheap and you are looking for prices that follow vanilla Factorio's exponential pricing model, look here: https://mods.factorio.com/mod/ImpatientsCharacterLogisticSlotsInfiniteResearch