Trash into Treasure: δ-FAPbI<sub>3</sub> Polymorph Stabilized MAPbI<sub>3</sub> Perovskite with Power Conversion Efficiency beyond 21.
basic_science · Level V
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- Record sourced from PubMed, PMID 29682798.
- Also identified by DOI 10.1002/adma.201707143.
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Abstract
Effective passivation and stabilization of both the inside and interface of a perovskite layer are crucial for perovskite solar cells (PSCs), in terms of efficiency, reproducibility, and stability. Here, the first formamidinium lead iodide (δ-FAPbI<sub>3</sub> ) polymorph passivated and stabilized MAPbI<sub>3</sub> PSCs are reported. This novel MAPbI<sub>3</sub> /δ-FAPbI<sub>3</sub> structure is realized via treating a mixed organic cation MA <sub>x</sub> FA<sub>1-</sub><sub>x</sub> PbI<sub>3</sub> perovskite film with methylamine (MA) gas. In addition to the morphology healing, MA gas can also induce the formation of δ-FAPbI<sub>3</sub> phase within the perovskite film. The in situ formed 1D δ-FAPbI<sub>3</sub> polymorph behaves like an organic scaffold that can passivate the trap state, tunnel contact, and restrict organic-cation diffusion. As a result, the device efficiency is easily boosted to 21%. Furthermore, the stability of the MAPbI<sub>3</sub> /δ-FAPbI<sub>3</sub> film is also obviously improved. This δ-FAPbI<sub>3</sub> phase passivation strategy opens up a new direction of perovskite structure modification for further improving stability without sacrificing efficiency.