How the Mixed Cations (Guanidium, Formamidinium, and Phenylethylamine) in Tin Iodide Perovskites Affect Their Charge Carrier Dynamics and Solar Cell Characteristics

Eita Nakanishi; Ryosuke Nishikubo; Atsushi Wakamiya; Akinori Saeki

doi:10.1021/acs.jpclett.0c00686

How the Mixed Cations (Guanidium, Formamidinium, and Phenylethylamine) in Tin Iodide Perovskites Affect Their Charge Carrier Dynamics and Solar Cell Characteristics

J Phys Chem Lett. 2020 May 21;11(10):4043-4051. doi: 10.1021/acs.jpclett.0c00686. Epub 2020 May 7.

Authors

Eita Nakanishi¹, Ryosuke Nishikubo¹, Atsushi Wakamiya², Akinori Saeki^{1

3}

Affiliations

¹ Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
² Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
³ Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.

PMID: 32378900
DOI: 10.1021/acs.jpclett.0c00686

Abstract

Despite recent interest in lead-free Sn iodide perovskite (ASnI₃) solar cells, the role of mixed A-site cations is yet to be fully understood. Here, we report the effect of the ternary mixing of organic A-site cations (guanidium, GA; formamidinium, FA; and phenylethylamine, PEA) on the solar cell performance and charge carrier dynamics that are evaluated using time-resolved microwave conductivity (TRMC). (GA_xFA_1-x)_0.9PEA_0.1SnI₃ exhibits the maximum power conversion efficiency (PCE) of 7.90% at x = 0.15 and a drastic decrease with increasing GA content. Notably, our TRMC measurements of ASnI₃ with/without a hole transport layer reveal the same trend with the devices. From the analyses, we suggest that a variation of electron mobility affected by the location of the GA cation in the grains significantly impacts the PCE. Our work sheds light on the role of mixed A-site cations and directs a route toward the further development of Sn perovskite solar cells.