PT Journal AU Wieghold, S Bieber, AS Lackner, J Nienhaus, K Nienhaus, GU Nienhaus, L TI One‐Step Fabrication of Perovskite‐Based Upconversion Devices SO ChemPhotoChem PY 2020 BP 704 EP 712 VL 4 IS 9 DI 10.1002/cptc.202000068 LA english ER