Presentation Information
[16a-K405-5]Inverted Perovskite Solar Cells Using Single-walled Carbon Nanotube Thin Film Electrodes
〇Yutaka Matsuo1,2, Naoki Ueoka1, Achmad Syarif Hidayat1, Hisayoshi Ohshima2, Yoshimasa Hijikata3 (1.Nagoya Univ., 2.InFuS, Nagoya Univ., 3.DENSO CORPORATION)
Keywords:
Carbon Nanotubes,Perovskite Solar Cells,Phosphine
In this presentation, we will focus on inverted perovskite solar cells (PSCs) and introduce the fabrication and evaluation of p-type (or n-type) single-walled carbon nanotube (SWCNT) thin-film electrodes as the lower transparent electrode or the upper back electrode.
First, the lower SWCNT thin-film transparent electrode was formed by a wet process using a spray coating method. Filter treatment before spray coating effectively reduced the carrier trap density and also had a flattening effect, making it possible to fabricate an inverted PSC. p-Doping with concentrated nitric acid vapor was more effective for wet-SWCNT thin films than for dry-SWCNT thin films fabricated by the floating catalyst CVD method. This is presumably because a small amount of water molecules remain near the defects in wet-SWCNTs, where the evaporated HNO3 molecules are concentrated, resulting in a strong p-doping effect. For this reason, wet-SWCNTs gave better results than dry-SWCNTs.
Next, for the back electrode of the upper semi-transparent SWCNT thin film, a dry-SWCNT thin film that can be transferred onto the device was used. Normally, SWCNTs are p-doped with oxygen in the air, so we hoped to de-dope the oxygen with a phosphine compound and then n-dope the SWCNTs by influx of electrons from the lone pair of phosphine. When we measured the Seebeck coefficient, it was found to be a negative value, indicating that the SWCNTs were indeed n-doped. However, since phosphines are insulators in this state, it was necessary to remove the excess dopant, and by replacing the excess dopant with a fullerene derivative, we were able to use the SWCNTs as an n-type electrode.
First, the lower SWCNT thin-film transparent electrode was formed by a wet process using a spray coating method. Filter treatment before spray coating effectively reduced the carrier trap density and also had a flattening effect, making it possible to fabricate an inverted PSC. p-Doping with concentrated nitric acid vapor was more effective for wet-SWCNT thin films than for dry-SWCNT thin films fabricated by the floating catalyst CVD method. This is presumably because a small amount of water molecules remain near the defects in wet-SWCNTs, where the evaporated HNO3 molecules are concentrated, resulting in a strong p-doping effect. For this reason, wet-SWCNTs gave better results than dry-SWCNTs.
Next, for the back electrode of the upper semi-transparent SWCNT thin film, a dry-SWCNT thin film that can be transferred onto the device was used. Normally, SWCNTs are p-doped with oxygen in the air, so we hoped to de-dope the oxygen with a phosphine compound and then n-dope the SWCNTs by influx of electrons from the lone pair of phosphine. When we measured the Seebeck coefficient, it was found to be a negative value, indicating that the SWCNTs were indeed n-doped. However, since phosphines are insulators in this state, it was necessary to remove the excess dopant, and by replacing the excess dopant with a fullerene derivative, we were able to use the SWCNTs as an n-type electrode.
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