Highest weight representations of $U_q(\hat{sl}(2|1))$ and correlation   functions of the q-deformed supersymmetric t-J model
  We re-examine the level-one irreducible highest weight representations of the quantum affine superalgebra $U_q(\hat{sl}(2|1))$ and derive the characters and supercharacters associated with these representations. We calculate the exchange relations of the vertex operators and find that these vertex operators satisfy the graded Faddeev-Zamolodchikov algebra. We give an integral expression of the correlation functions of the q-deformed supersymmetric t-J model and derive the difference equations which they satisfy. 
Wen-Li Yang and Yao-Zhong Zhang