Improved reverse bias stability in p–i–n perovskite solar cells with optimized hole transport materials and less reactive electrodes by Jiang, F, Shi, Y, Rana, TR, Morales, D, Gould, IE, McCarthy, DP, Smith, JA, Christoforo, MG, Yaman, MY, Mandani, F, Terlier, T, Contreras, H, Barlow, S, Mohite, AD, Snaith, HJ, Marder, SR, MacKenzie, JD, McGehee, MD, Ginger, DS