Toward Revealing the Critical Role of Perovskite Coverage
in Highly Efficient Electron-Transport Layer-Free Perovskite Solar
Cells: An Energy Band and Equivalent Circuit Model Perspective
posted on 2016-03-29, 00:00authored byLike Huang, Jie Xu, Xiaoxiang Sun, Yangyang Du, Hongkun Cai, Jian Ni, Juan Li, Ziyang Hu, Jianjun Zhang
Currently,
most efficient perovskite solar cells (PVKSCs) with a p–i–n
structure require simultaneously electron transport layers (ETLs)
and hole transport layers (HTLs) to help collecting photogenerated
electrons and holes for obtaining high performance. ETL free planar
PVKSC is a relatively new and simple structured solar cell that gets
rid of the complex and high temperature required ETL (such as compact
and mesoporous TiO2). Here, we demonstrate the critical
role of high coverage of perovskite in efficient ETL free PVKSCs from
an energy band and equivalent circuit model perspective. From an electrical
point of view, we confirmed that the low coverage of perovskite does
cause localized short circuit of the device. With coverage optimization,
a planar p–i–n++ device with a power conversion
efficiency of over 11% was achieved, implying that the ETL layer may
not be necessary for an efficient device as long as the perovskite
coverage is approaching 100%.