Photoinduced Self-Gating of Perovskite Photovoltaic Cells in Ionic Liquid

Grigorii Verkhogliadov; Abolfazl Mahmoodpoor; Pavel Voroshilov; Ross Haroldson; Masoud Alahbakhshi; Albert G Nasibulin; Sergey V Makarov; Anvar A Zakhidov

doi:10.1021/acsmaterialsau.3c00006

Photoinduced Self-Gating of Perovskite Photovoltaic Cells in Ionic Liquid

ACS Mater Au. 2023 Apr 20;3(4):337-350. doi: 10.1021/acsmaterialsau.3c00006. eCollection 2023 Jul 12.

Authors

Grigorii Verkhogliadov^{1

2}, Abolfazl Mahmoodpoor², Pavel Voroshilov², Ross Haroldson¹, Masoud Alahbakhshi³, Albert G Nasibulin⁴, Sergey V Makarov^{2

5}, Anvar A Zakhidov^{2

1}

Affiliations

¹ Physics Department and The NanoTech Institute, The University of Texas at Dallas, Richardson, Texas 75080, United States.
² School of Physics and Engineering, ITMO University, Kronverkskiy pr. 49, 197101 St. Petersburg, Russia.
³ Department of Electrical and Computer Engineering, The University of Texas at Dallas, Richardson, Texas 75080, United States.
⁴ Center for Photonics and Quantum Materials, Skolkovo University of Science and Technology, Moscow 143026, Russia.
⁵ Qingdao Innovation and Development Center, Harbin Engineering University, Qingdao 266000, Shandong China.

Abstract

We demonstrate that the power conversion efficiency (PCE), photocurrent, and fill factor (FF) of perovskite solar cells (PSC) can be significantly improved by the photoinduced self-gating in ionic liquids (ILs) via n-doping of the carbon nanotube (CNT) top electrode on the fullerene electron transport layer (ETL). CNTs, graphene, and other carbon electrodes have been proven to be stable electrodes for PSC, but efficiency was not high. We have previously shown that the performance of PSCs with CNT electrodes can be improved by IL gating with gate voltage (V_g) applied from an external power source. Here we demonstrate that effective self-gating in ILs is possible by a photoinduced process, without an external source. The open circuit voltage (V_oc) generated by the PSC itself can be applied to the CNT/C60 electrode as V_g leading to photogating. This self-gating with V_oc is compared to photocharging of CNTs in ILs without any gating for two types of fullerene ETLs: C₆₀ and C₇₀, Two types of ILs, DEME-TFSI and BMIM-BF₄, are tested for two types of nanotubes electrodes: single wall (SWCNT), and multiwall (MWCNT). The resulting improvements are analyzed using the effective diode-circuit (DC) and the drift-diffusion (DD) models. Self-gating allows the PCE improvement from 3-5% to 10-11% for PSCs with a thick ETL, while for optimal combination of a thin SWCNT/ETL with added layers for improved stability, the PCE reached 13.2% in DEME-TFSI IL.