Highly performing tin-based perovskite solar cells: a focus on the thin film quality
Maria Antonietta Loi a
a University of Groningen - NL, Nijenborgh, 4, Groningen, Netherlands
Invited Speaker, Maria Antonietta Loi, presentation 019
DOI: https://doi.org/10.29363/nanoge.iperop.2020.019
Publication date: 14th October 2019

Organic lead halide perovskite based solar cells (HPSCs) have achieved certified power conversion efficiency (PCE) over 25.0%. Despite the high efficiency achieved, there are still many concerns about the large-scale applicability of these solar cells because of their Pb2+ content. The simpler approach to address this issue is to find a benign or less toxic metal to replace the lead atom in the perovskite structure, obtaining a perovskite displaying similar excellent optical and electrical properties as the Pb-based compounds.

Tin based perovskite holds the promise to give rise to similar or even higher PCE compared to their Pb counterpart. However, for relatively long time the tin-based HPSCs held a PCE lower than 7% though intensive research efforts were devoted to their investigation. The facile formation of tin vacancies and easy oxidation of Sn2+ have been identified as the main reason determining the low PCE.

In my presentation I will report as a small amount of 2D tin perovskite templates the growth of highly crystalline and oriented 3D FASnI3 grains (2D/3D mixtures), suppressing effectively the appearance of tin vacancies and Sn2+ oxidation. [[1]] As a consequence of the reduced background charge carrier density and trap assisted charge recombination, the device showed a 50% improvement in the PCE (up to 9%) compared to that using pure 3D tin perovskite. We further succeeded reducing the defects in the 2D/3D tin perovskite films by adding ethylammonium iodide (EAI) into the corresponding perovskite precursor solution even starting from precursors of limited purity [2]. These films display larger crystalline grains and a more compact and uniform film morphology when compared to their counterparts without EA cation. These features lead to a much lower trap density, background charge carrier density and charge recombination loss in the corresponding devices. Results, which allow hopping for future highly efficient Sn-based hybrid perovskite solar cells.


 

 

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