Double-sided annealing to reverse the crystallization direction for efficient and stable flexible FACs-perovskite solar modules.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41270165.
- Also identified by DOI 10.1126/sciadv.adz0962 and PMC identifier 12637302.
- Licence recorded as CC BY-NC.
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Abstract
The application of methylammonium cations makes flexible perovskite solar modules (<i>f</i>-PSMs) unstable in long term. Here, we report flexible p-i-n structure perovskite modules made of methylammonium-free formamidinium cesium lead iodide (FA<sub>1-</sub><sub><i>x</i></sub>Cs<i><sub>x</sub></i>PbI<sub>3</sub>, <i>x</i> ≤ 0.1) to improve their stability. Interfacial voids between FA<sub>1-</sub><sub><i>x</i></sub>Cs<i><sub>x</sub></i>PbI<sub>3</sub> layer and hole-transport layers, caused by the limited annealing temperature for <i>f</i>-PSMs, severely disrupt the film structural continuity. A double-sided annealing strategy is used to address this challenge, which markedly reduces the voids at the buried interface and yields homogeneous perovskite films with enlarged grains. The double-sided annealing can flip the phase transition direction from traditional top-down to bottom-up, because of the much higher air temperature above perovskite films, allowing a quick dimethyl sulfoxide evaporation. The <i>f</i>-PSMs achieve an aperture-area power conversion efficiency (PCE) of 19.1% and show ~10% efficiency loss after 107 thermal cycles between -40° and 85°C. The small-area devices retained over 98% of their initial PCE after 1176 hours under one Sun illumination at 85°C.