OSA-Direct
Wednesday, 20 Sep 2017

Researchers develop low-bandgap tandem perovskite tandem solar

The researchers report that their low-band-gap perovskite solar cells achieved a maximum power conversion efficiency of 17.6% and a certified efficiency of 17.01%

20 Apr 2017 | Editor

Researchers at The University of Toledo have announced they have developed an all-perovskite tandem solar cell that has reportedly achieved "world-record" conversion efficiency for a solar cell that uses less toxic lead. The researchers said that their less-toxic device combines two different solar cells to harvest different parts of the solar spectrum, resulting in increased total electrical power generated.

Dr. Yanfa Yan and his co-authors reported efficient mixed tin-lead iodide low-band gap (∼1.25 eV) perovskite solar cells with open-circuit voltages up to 0.85 V and over 70% external quantum efficiencies in the infrared wavelength range of 700–900 nm, delivering a short-circuit current density of over 29 mA cm−2 and demonstrating suitability for bottom-cell applications in all-perovskite tandem solar cells. The research findings have been published in Nature Energy (see below for details).

In the paper the researchers report that their low-band-gap perovskite solar cells achieved a maximum power conversion efficiency of 17.6% and a certified efficiency of 17.01% with a negligible current–voltage hysteresis. When mechanically stacked with a ∼1.58 eV band gap perovskite top cell, their "best" all-perovskite 4-terminal tandem solar cell showed a steady-state efficiency of 21.0%.

According to the researchers the next step would be to further improve the performance of their bottom cell and the performance of the tandem cells, including both four-terminal and two-terminal ones.

University of Toledo - All-perovskite tandem solar cell

Figure: University of Toledo - All-perovskite tandem solar cell

The researchers collaborated with colleagues in the Wright Center for Photovoltaics Innovation and Commercialization at the University of Toledo.

Yanfa Yan, PhD, Ohio Research Scholar chair and UT professor of physics, said, "We developed a process to fabricate efficient bottom cells using mixed Sn-Pb perovskite absorbers." Yanfa continued, "The fabrication of the efficient bottom cell had not been accomplished before, is what is truly innovative about this research work. Our all-perovskite solar cells have the so-called four-terminal structure, which stacks a wide-band-gap top cell with a low-band-gap bottom cell. The current all-perovskite tandem cells are limited by the lack of efficient bottom cell."
Yanfa concluded by saying, "The performance of the all-perovskite tandem solar cell indeed presents a paradigm shift: Our mixed Sn-Pb perovskite thin films exhibit very high quality, showing long carrier lifetimes and allows us to use thick enough perovskite layers to efficiently absorber photons in the long wavelength range, adding that the record-breaking technology has the potential to produce low-cost solar electricity."

Low-bandgap mixed tin–lead iodide perovskite absorbers with long carrier lifetimes for all-perovskite tandem solar cells

Dewei Zhao | Yue Yu | Changlei Wang | Weiqiang Liao | Niraj Shrestha | Corey R. Grice | Alexander J. Cimaroli | Lei Guan | Randy J. Ellingson | Kai Zhu, Xingzhong Zhao | Ren-Gen Xiong | Yanfa Yan

Nature Energy 2 | Article number: 17018 (2017) | doi:10.1038/nenergy.2017.18

Received: 25 October 2016 | Accepted: 26 January 2017 | Published online: 01 March 2017

Abstract

Tandem solar cells using only metal-halide perovskite sub-cells are an attractive choice for next-generation solar cells. However, the progress in developing efficient all-perovskite tandem solar cells has been hindered by the lack of high-performance low-bandgap perovskite solar cells. Here, we report efficient mixed tin–lead iodide low-bandgap (∼1.25 eV) perovskite solar cells with open-circuit voltages up to 0.85 V and over 70% external quantum efficiencies in the infrared wavelength range of 700–900 nm, delivering a short-circuit current density of over 29 mA cm−2 and demonstrating suitability for bottom-cell applications in all-perovskite tandem solar cells. Our low-bandgap perovskite solar cells achieve a maximum power conversion efficiency of 17.6% and a certified efficiency of 17.01% with a negligible current–voltage hysteresis. When mechanically stacked with a ∼1.58 eV bandgap perovskite top cell, our best all-perovskite 4-terminal tandem solar cell shows a steady-state efficiency of 21.0%.

www.utoledo.edu   


About University of Toledo

Source: University of Toledo


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