Ion-induced field screening as a dominant factor in perovskite solar cell operational stability by Thiesbrummel, J, Shah, S, Gutierrez-Partida, E, Zu, F, Peña-Camargo, F, Zeiske, S, Diekmann, J, Ye, F, Peters, KP, Brinkmann, KO, Caprioglio, P, Dasgupta, A, Seo, S, Adeleye, FA, Warby, J, Jeangros, Q, Lang, F, Zhang, S, Albrecht, S, Riedl, T, Armin, A, Neher, D, Koch, N, Wu, Y, Snaith, H