Performance and Stability Enhancement of Dye-Sensitized and Perovskite Solar Cells by Al Doping of TiO2 by Pathak, S, Abate, A, Ruckdeschel, P, Roose, B, Goedel, K, Vaynzof, Y, Santhala, A, Watanabe, S, Hollman, D, Noel, N, Sepe, A, Wiesner, U, Friend, R, Snaith, H, Steiner, U