Abstract
The stunning rise of methylammonium lead iodide perovskite material as a light harvesting material in recent years has drawn much attention in the photovoltaic community. Here, we investigated in detail the uniform and void-free perovskite capping layer in the mesoscopic perovskite devices and found it to play a critical role in determining device performance and charge recombination process. Compared to the rough surface with voids of the perovskite layer, surface of the perovskite capping layer obtained from sequential deposition process is much more uniform with less void formation and distribution within the TiO2 mesoscopic scaffold is more homogeneous, leading to much improved photovoltaic parameters of the devices. The impact of void free perovskite capping layer surface on the charge recombination processes within the mesoscopic perovskite solar cells is further scrutinized via charge extraction measurement. Modulation of precursor solution concentrations in order to further improve the perovskite layer surface morphology leads to higher efficiency and lower charge recombination rates. Inhibited charge recombination in these solar cells also matches with the higher charge density and slower photovoltage decay profiles measured.
| Original language | English |
|---|---|
| Pages (from-to) | 4181-4193 |
| Number of pages | 13 |
| Journal | Nanoscale |
| Volume | 8 |
| Issue number | 7 |
| DOIs | |
| State | Published - Feb 21 2016 |
| Externally published | Yes |
Funding
K. Fu would like to acknowledge valuable discussions from Dr Wolfgang Tress and Dr Robin Humphry-Baker. This work is supported by National Research Foundation (NRF) Singapore under the Competitive Research Program (CRP) and the Singapore-Berkeley Research Initiative for Sustainable Energy (SinBeRISE) CREATE Programme. Work at the Molecular Foundry at Lawrence Berkeley National Laboratory was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.