Abstract
The preferential growth of α-phase formamidinium perovskite (α-FAPbI3) at low temperatures can be achieved with the incorporation of chloride-based additives, with methylammonium chloride (MACl) being the most common example. However, compared to other less-volatile chloride additives, MACl only remains in the growing perovskite film for a short time before evaporating during annealing, primarily influencing the early stages of film formation. In addition, evaporation of MACl as methylamine (MA0) and HCl can introduce a side reaction between MA0 and formamidinium (FA), undermining the compositional purity and phase stability of α-FAPbI3. In this study, it is demonstrated that addition of iodine (I2) into the FAPbI3 precursor solution containing MACl suppresses the MA-FA side reaction during annealing. Additionally, MACl evaporation is delayed owing to strong interaction with triiodide. The added I2 facilitates spontaneous growth of α-FAPbI3 prior to annealing, with an improved bottom morphology due to the formation of fewer byproducts. Perovskite solar cells derived from an I2-incorporated solution deliver a champion power conversion efficiency of 25.2% that is attributed to suppressed non-radiative recombination.
Original language | English (US) |
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Article number | 2400500 |
Journal | Advanced Energy Materials |
Volume | 14 |
Issue number | 25 |
DOIs | |
State | Published - Jul 5 2024 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- General Materials Science
Keywords
- iodine
- methylammonium chloride
- perovskite precursor solution