Strong Photocurrent Amplification in Perovskite Solar Cells with a Porous TiO2 Blocking Layer under Reverse Bias

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• 作者：Thomas Moehl ; Jeong Hyeok Im ; Yong Hui Lee ; Konrad Domanski ; Fabrizio Giordano ; Shaik M. Zakeeruddin ; M. Ibrahim Dar ; Leo-Philipp Heiniger ; Mohammad Khaja Nazeeruddin ; Nam-Gyu Park ; Michael Gr盲tzel
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2014
• 出版时间：November 6, 2014
• 年：2014
• 卷：5
• 期：21
• 页码：3931-3936
• 全文大小：371K
• ISSN：1948-7185

文摘

We investigate two different types of TiO₂ blocking layer (BL) deposition techniques commonly used in solid-state methylammonium lead triiodide perovskite (MaPbI₃)-based solar cells. Although these BLs lead to similar photovoltaic device performance, their structure and blocking capability is actually very different. In one case, the 鈥渂locking鈥?layer is porous, allowing an intimate contact of the perovskite with the fluorine-doped tin-dioxide (FTO)-covered glass substrate serving as transparent electron collector. This interface between the perovskite and the FTO shows rectifying behavior. Reverse biasing of such a solar cell allows the determination of the valence-band position of the MaPbI₃ and the theoretical maximum attainable photovoltage. We show that under reverse bias strong photocurrent amplification is observed, permitting the cell to work as a high-gain photodetector at low voltage. Without BL, the solar-cell performance decreased, but the photocurrent amplification increased. At 1 V reverse bias, the photocurrent amplification is above a factor of 10 for AM 1.5 solar light and over 100 for lower light intensities.

Keywords:

MaPbI₃ perovskite solar cell; porous blocking layer; valence band position; photocurrent amplification; low-voltage high-gain photodetector