Low-Temperature Remote Plasma Synthesis of Highly Porous TiO$_2$ as Electron Transport Layers in Perovskite Solar Cells
Year: 2025
Type: preprint
Abstract: Halide perovskite solar cells (PSCs) offer high efficiency and low costs, making them key for future photovoltaics. Optimizing charge transport layers is crucial, with porous TiO$_2$ widely used as electron transport layers (ETL) due to its energy alignment, transparency, and abundance. However, its efficiency relies on crystallinity requiring high-temperature processing (>450$^\circ$C), increasing costs and limiting flexible substrates. Low-temperature wet-chemical methods face scalability issues due to material waste and hazardous solvents. In this context, plasma-based technologies are emerging as a more efficient and sustainable alternative to oxide-based ETLs. This study presents the synthesis of TiO$_2$ layers using an advanced plasma method combining remote plasma-assisted vacuum deposition (RPAVD) and soft plasma etching (SPE) at mild temperatures (<200$^\circ$C), allowing control of microstructure and porosity. The resulting nanocolumnar film, decorated with a highly porous aerogel-like layer, enhances optical and electronic properties. These plasma-synthesized TiO$_2$ layers are antireflective and improve the efficiency in porous n-i-p PSCs, matching the performance of high-temperature reference cells. These PSCs achieve a champion PCE of 14.6%, a high value compared to reference devices synthesized at 450{\deg}C. Impedance spectroscopy confirms high recombination resistance and stable capacitance, linked to improved perovskite crystallinity. Our results highlight the potential of the RPAVD+SPE approach for producing low-temperature efficient ETLs, providing a feasible, industrially scalable, and eco-friendly alternative for manufacturing flexible, high-performance photovoltaic devices.
Source: arXiv (Cornell University)
Authors: Obrero-Perez, Jose M., Nunez-Galvez, Fernando, Contreras-Bernal, Lidia, Castillo-Seoane, Javier, Moreno, Gloria P., Czermak, Triana, Aparicio, Francisco J., Rojas, Teresa C., Ferrer, Francisco J., Borras, Ana, Barranco, Angel, Sanchez-Valencia, Juan R
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6979336144
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