Yb_1-xSm_xBa₂Cu₃O_7-d films have been prepared by chemical solution deposition following the Extremely-Low-Fluorine route, which allows reducing the fluorine content by 93% with respect to standard TFA solutions. The obtained results show that, on the one hand, T_c remains stable at ~ 90 K with Sm content up to x = 0.5 where T_c starts to increase towards the values of pure SmBCO films of ~ 95 K. On the other hand, the critical current densities J_c of the pure SmBCO films are the largest at 77 K, where the influence of a higher T_c is very relevant, while at lower temperatures and low fields, the mixed films reach larger values. This demonstrates that mixing rare earth elements RE in REBa₂Cu₃O_7-d causes a change in the pinning properties of the films and reveals the importance of selecting adequate REBCO compounds according to the temperature and magnetic field region where a specific application operates.