High-Efficiency Flexible Perovskite Solar Cells Enabled by an Ultrafast Room-Temperature Reactive Ion Etching Process

Abstract

Perovskite solar cells (PSCs), which have surprisingly emerged in recent years, are now aiming at commercialization. Rapid, low-temperature, and continuous fabrication processes that can produce high-efficiency PSCs with a reduced fabrication cost and shortened energy payback time are important challenges on the way to commercialization. Herein, we report a reactive ion etching (RIE) method, which is an ultrafast room-temperature technique, to fabricate mesoporous TiO2 (mp-TiO2) as an electron transport layer for high-efficiency PSCs. Replacing the conventional high-temperature annealing process by RIE reduces the total processing time for fabricating 20 PSCs by 40%. Additionally, the RIE-processed mp-TiO2 exhibits enhanced electron extraction, whereupon the optimized RIE-mp-TiO2-based PSC exhibits a power conversion efficiency (PCE) of 19.60% without J–V hysteresis, when the devices were optimized with a TiCl4 surface treatment process. Finally, a flexible PSC employing RIE-mp-TiO2 is demonstrated with 17.29% PCE. Considering that the RIE process has been actively used in the semiconductor industry, including for the fabrication of silicon photovoltaic modules, the process developed in this work could be easily applied toward faster, simpler, and cheaper manufacturing of PSC modules.

Intermediate Phase‐Free Process for Methylammonium Lead Iodide Thin Film for High‐Efficiency Perovskite Solar Cells

“…[ 1 ] The rapid improvement in PCE of PSCs is mainly accompanied by the advances in fabrication process such as solvent engineering strategy, [ 2 ] as well as the developments in desirable composition of light absorptionmaterial such as mixed‐halide and mixed cation perovskites, [ 3 ] and device configuration with new charge transport layers. [ 4 ]…”

Perovskite Solar Cells with Low-Cost TiO2 Mesoporous Photoanodes Prepared by Rapid Low-Temperature (70 °C) Plasma Processing

“…A lowpressure approach, however, appears very promising and was recently demonstrated by Kim et al, who used radio-frequency reactive ion etching in Ar/O 2 plasma at 200 mTorr to achieve removal of organic binder species in m-TiO 2 . 34 Similarly, Nam et al employed low-pressure RF oxygen plasma treatment combined with TiCl 4 treatment to improve the efficiency of PSC with an m-TiO 2 electron-transporting layer. 35 The topic of surface modification of TiO 2 layers in perovskite solar cells has been comprehensively reviewed by Hu et al 36 Further, this decade has seen a shift in industrial focus toward the treatment of surfaces and nanostructured coatings of large areas, up to hundreds of square meters, manufactured in a time-efficient, roll-to-roll manner.…”

“…The process of low-pressure plasma treatment of mesoporous TiO 2 , is inappropriate for low-cost production because it is relatively slow and requires complex vacuum systems. A low-pressure approach, however, appears very promising and was recently demonstrated by Kim et al, who used radio-frequency reactive ion etching in Ar/O 2 plasma at 200 mTorr to achieve removal of organic binder species in m-TiO 2 . Similarly, Nam et al employed low-pressure RF oxygen plasma treatment combined with TiCl 4 treatment to improve the efficiency of PSC with an m-TiO 2 electron-transporting layer .…”

Flexible Perovskite Solar Cells: From Materials and Device Architectures to Applications

“…Mesoporous TiO 2 -based PSCs have been developed for many years with mature fabrication technology. − Kim et al developed a low-temperature method to prepare mesoporous TiO 2 . Mesoporous TiO 2 was spin coated on a compact TiO 2 layer together with an organic binder to form a paste at 80 °C.…”