Crystal Morphologies of Organolead Trihalide in Mesoscopic/Planar Perovskite Solar Cells.
The crystal morphology of organolead trihalide perovskite (OTP) light absorbers can have profound influence on the perovskite solar cells (PSCs) performance. Here we have used a combination of conventional transmission electron microscopy (TEM) and high-resolution TEM (HRTEM), in cross-section and plan-view, to characterize the morphologies of a solution-processed OTP (CH3NH3PbI3 or MAPbI3) within mesoporous TiO2 scaffolds and within capping and planar layers. Studies of TEM specimens prepared with and without the use of focused ion beam (FIB) show that FIBing is a viable method for preparing TEM specimens. HRTEM studies, in conjunction with quantitative X-ray diffraction, show that MAPbI3 perovskite within mesoporous TiO2 scaffold has equiaxed grains of size 10-20 nm and relatively low crystallinity. In contrast, the grain size of MAPbI3 perovskite in the capping and the planar layers can be larger than 100 nm in our PSCs, and the grains can be elongated and textured, with relatively high crystallinity. The observed differences in the performance of planar and mesoscopic-planar hybrid PSCs can be attributed in part to the striking differences in their perovskite-grain morphologies.
†School of Engineering, Brown University, 184 Hope Street, Providence, Rhode Island 02912, United States.
Yuanyuan
Y
Zhou
†School of Engineering, Brown University, 184 Hope Street, Providence, Rhode Island 02912, United States.
Alexander L
AL
Vasiliev
†School of Engineering, Brown University, 184 Hope Street, Providence, Rhode Island 02912, United States.
Wenwen
W
Wu
‡Chemical and Materials Science Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States.
Mengjin
M
Yang
§Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101, P.R. China.
Shuping
S
Pang
‡Chemical and Materials Science Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States.
Kai
K
Zhu
†School of Engineering, Brown University, 184 Hope Street, Providence, Rhode Island 02912, United States.
Nitin P
NP
Padture
D017610:Calcium Compounds / Q000737:chemistry*; D008744:Methylamines / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D009942:Organometallic Compounds / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D016062:Porosity; D012993:Solar Energy; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
D017610:Calcium Compounds; D008744:Methylamines; D009942:Organometallic Compounds; D010087:Oxides; C059910:perovskite; C027451:methylamine; D014025:Titanium
HRTEM; XRD; focused ion beam; morphology; transmission electron microscopy