Multichannel Interdiffusion Driven FASnI<sub>3</sub> Film Formation Using Aqueous Hybrid Salt/Polymer Solutions toward Flexible Lead-Free Perovskite Solar Cells.
basic_science · Level V
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- Record sourced from PubMed, PMID 28397337.
- Also identified by DOI 10.1002/adma.201606964.
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Abstract
Tin (Sn)-based perovskites are increasingly attractive because they offer lead-free alternatives in perovskite solar cells. However, depositing high-quality Sn-based perovskite films is still a challenge, particularly for low-temperature planar heterojunction (PHJ) devices. Here, a "multichannel interdiffusion" protocol is demonstrated by annealing stacked layers of aqueous solution deposited formamidinium iodide (FAI)/polymer layer followed with an evaporated SnI<sub>2</sub> layer to create uniform FASnI<sub>3</sub> films. In this protocol, tiny FAI crystals, significantly inhibited by the introduced polymer, can offer multiple interdiffusion pathways for complete reaction with SnI<sub>2</sub> . What is more, water, rather than traditional aprotic organic solvents, is used to dissolve the precursors. The best-performing FASnI<sub>3</sub> PHJ solar cell assembled by this protocol exhibits a power conversion efficiency (PCE) of 3.98%. In addition, a flexible FASnI<sub>3</sub> -based flexible solar cell assembled on a polyethylene naphthalate-indium tin oxide flexible substrate with a PCE of 3.12% is demonstrated. This novel interdiffusion process can help to further boost the performance of lead-free Sn-based perovskites.