High Open-Circuit Voltage Cs2AgBiBr6 Carbon-Based Perovskite Solar Cells Via Green Processing of Ultrasonic Spray-Coated Carbon Electrodes from Waste Tire Sources
Fabian Schmitz a b, Teresa Gatti a b
a Center for Materials Research, Justus Liebig University, Heinrich-Buff-Ring 17, 35392, Giessen, Germany
b Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
València, Spain, 2022 May 19th - 25th
Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson
Oral, Fabian Schmitz, presentation 117
DOI: https://doi.org/10.29363/nanoge.hopv.2022.117
Publication date: 20th April 2022

Although top-notch lead-based perovskite solar cells (PSCs) achieve power conversion efficiencies (PCEs) >25%, they are still hindered from commercial implementation by their low environmental stability, high toxicity and optimizable costs. The latter could be reduced by eliminating the metal back electrode, typically consisting of vacuum-deposited gold, as well as the hole-transport material by substituting both with a conductive carbon material to create carbon-based PSCs (C-PSCs).[1] Furthermore, the utilization of perovskite materials based on other metallic compounds could tackle the other two issues of stability and toxicity. A promising example that combines both high environmental stability and low toxicity is the double perovskite Cs2AgBiBr6. On the one hand, this material is characterized by an advantageous carrier lifetime of more than 1 µs.[2] On the other hand, its large indirect bandgap,[3] fast surface charge carrier recombination[4] as well as strong electron-phonon coupling and exciton binding energy[5] suppress the PCE of Cs2AgBiBr6-based PSCs what emphasizes the need of further compositional or morphological engineering to overcome those drawbacks.

In our work, we present the deposition of “green” carbon electrodes onto Cs2AgBiBr6 thin films via high-throughput ultrasonic spray coating to prepare lead-free C-PSCs. To achieve a sustainable approach, we started from a carbon material obtained from the hydrothermal recycling of waste tires and dispersed it in isopropanol to create an additive-free carbon ink. This ink worked as a precursor for the upscalable ultrasonic spray deposition method to fabricate carbon electrodes under ambient atmosphere and at a low substrate temperature. Through this procedure we obtained C-PSCs with record open-circuit voltages of >1.2 V, which might represent ultra-cheap solutions to power the indoor Internet of Things ecosystem.

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