Abstract
Though formamidinium lead triiodide (FAPbI3) possesses a suitable band gap and good thermal stability, the phase transition from the pure black perovskite phase (α-phase) to the undesirable yellow nonperovskite polymorph (δ-phase) at room temperature, especially under humid air, hinders its practical application. Here, we investigate the intrinsic instability mechanism of the α-phase at ambient temperature and demonstrate the existence of an anisotropic strained lattice in the (111) plane that drives phase transformation into the δ-phase. Methylammonium bromide (MABr) alloying (or FAPbI3-MABr) was found to cause lattice contraction, thereby balancing the lattice strain. This led to dramatic improvement in the stability of α-FAPbI3. Solar cells fabricated using FAPbI3-MABr demonstrated significantly enhanced stability under the humid air.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1014-1020 |
| Number of pages | 7 |
| Journal | ACS Energy Letters |
| Volume | 1 |
| Issue number | 5 |
| DOIs | |
| State | Published - Nov 11 2016 |
| Externally published | Yes |
Bibliographical note
Funding Information:The authors acknowledge financial support from the Institute of Critical Technology and Applied Science (ICTAS). S.P. and X.Z. would also like to acknowledge financial support from the Office of Naval Research through the MURI program. S.K.J. was supported through the Office of Naval Research participation in NSF I/UCRC: Center for Energy Harvesting Materials and Systems (CEHMS). The work at the National Renewable Energy Laboratory is supported by the U.S. Department of Energy under Contract No. DE-AC36-08-GO28308. K.Z. and Z.L. acknowledge support by the hybrid perovskite solar cell program of the National Center for Photovoltaics funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies Office.
Publisher Copyright:
© 2016 American Chemical Society.
