Controllable Growth of Perovskite Films by Room-Temperature Air Exposure for Efficient Planar Heterojunction Photovoltaic Cells.
A two-step solution processing approach has been established to grow void-free perovskite films for low-cost high-performance planar heterojunction photovoltaic devices. A high-temperature thermal annealing treatment was applied to drive the diffusion of CH3NH3I precursor molecules into a compact PbI2 layer to form perovskite films. However, thermal annealing for extended periods led to degraded device performance owing to the defects generated by decomposition of perovskite into PbI2. A controllable layer-by-layer spin-coating method was used to grow "bilayer" CH3NH3I/PbI2 films, and then drive the interdiffusion between PbI2 and CH3NH3I layers by a simple air exposure at room temperature for making well-oriented, highly crystalline perovskite films without thermal annealing. This high degree of crystallinity resulted in a carrier diffusion length of ca. 800 nm and a high device efficiency of 15.6%, which is comparable to values reported for thermally annealed perovskite films.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (USA).
Bin
B
Yang
Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996 (USA).
Ondrej
O
Dyck
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (USA).
Jonathan
J
Poplawsky
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (USA).
Jong
J
Keum
Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, TN, 37996 (USA).
Sanjib
S
Das
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (USA).
Alexander
A
Puretzky
Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (USA).
Tolga
T
Aytug
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (USA).
Pooran C
PC
Joshi
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (USA).
Christopher M
CM
Rouleau
Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996 (USA).
Gerd
G
Duscher
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (USA).
David B
DB
Geohegan
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (USA). xiaok@ornl.gov.
Kai
K
Xiao
air exposure; in situ X-ray diffraction; perovskites; photovoltaic devices; thin films