Liao, H.-C.H.-C.LiaoTsao, C.-S.C.-S.TsaoJao, M.-H.M.-H.JaoShyue, J.-J.J.-J.ShyueHsu, C.-P.C.-P.HsuHuang, Y.-C.Y.-C.HuangTian, K.-Y.K.-Y.TianChen, C.-Y.C.-Y.ChenSu, C.-J.C.-J.SuSu, W.-F.W.-F.SuWEI-FANG SU2018-09-102018-09-102015http://www.scopus.com/inward/record.url?eid=2-s2.0-84928947371&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/395682A hierarchical pore network in planar CH3NH3PbI3 perovskite is demonstrated herein. Quantitative characterizations by grazing incidence small angle X-ray scattering (GISAXS) with modeling and complementary microscopic observations provide insight at various length scales. It is a pore structure comprised of nano-scaled primary pores aggregating into meso-scaled fractal networks within the perovskite layer. Its structural evolution and mechanistic interpretation are explored with respect to different preparation methods/steps. The time-of-flight secondary ion mass spectrometer (TOF-SIMS) results suggest the infiltration of hole transporting materials (HTM) or electron transporting materials (ETM) deposited on top at different length scales. The inter-penetrating perovskite/HTM or perovskite/ETM form i-p or i-n one-sided porous heterojunctions, respectively, over the typically regarded planar-stacked heterojunction. They show distinctive photovoltaic characteristics and behaviors in which the large i-n interfaces at the nanoscale lead to highly efficient, hysteresis-free and reliable solar cell devices. The morphology-performance correlation is helpful for associated design of device architecture and processing toward higher efficiency and stability. © 2015 The Royal Society of Chemistry.[SDGs]SDG7Characterization; Fractal dimension; Heterojunctions; Nanostructured materials; Perovskite; Secondary ion mass spectrometry; Solar power generation; X ray scattering; Electron transporting materials; Grazing incidence small-angle X-ray scattering; Hole-transporting materials; Mechanistic interpretations; Microscopic observations; Photovoltaic characteristics; Quantitative characterization; Secondary ion mass spectrometers; Solar cellsjournal article10.1039/c5ta02184g