Superfast Room-Temperature Activation of SnO2 Thin Films via Atmospheric Plasma Oxidation and their Application in Planar Perovskite Photovoltaics

Abstract

The power conversion efficiency (PCE) of perovskite solar cells (PSCs) has now exceeded 20%; thus, research focus has shifted to establishing the foundations for commercialization. One of the pivotal themes is to curtail the overall fabrication time, to reduce unit cost, and mass-produce PSCs. Additionally, energy dissipation during the thermal annealing (TA) stage must be minimized by realizing a genuine low-temperature (LT) process. Here, tin oxide (SnO₂) thin films (TFs) are formulated at extremely high speed, within 5 min, under an almost room-temperature environment (<50 °C), using atmospheric Ar/O₂ plasma energy (P-SnO₂) and are applied as an electron transport layer of a "n–i–p"-type planar PSC. Compared with a thermally annealed SnO₂ TF (T-SnO₂), the P-SnO₂ TF yields a more even surface but also outstanding electrical conductivity with higher electron mobility and a lower number of charge trap sites, consequently achieving a superior PCE of 19.56% in P-SnO₂-based PSCs. These findings motivate the use of a plasma strategy to fabricate various metal oxide TFs using the sol–gel route.

A tin oxide (SnO₂) electron transport layer for a perovskite solar cell is successfully fabricated at extremely high speeds at a genuinely low temperature using atmospheric Ar/O₂ plasma annealing. This plasma-annealed SnO₂ (P-SnO₂) exhibits outstanding electrical conductivity and charge-extraction ability compared to thermally-annealed SnO₂, consequently achieving a superior PCE of 19.56% in P-SnO₂-based PSCs.

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