Quantum groups at small roots of 1

Question

I wonder if there is any literature about representations of quantum groups at a root of 1 of small order. For example, I would like to understand the case of $\mathrm{SL}(2)$ and $q=-1$ (in the appropriate normalization). In this case any irreducible representation is a pull-back from the classical group by means of Lusztig Frobenius, but this pull-back is not an equivalence of categories — the category of representations of this quantum group is not semi-simple. I would like to understand the Ext's between irreducible representations in this category.