Advancement in Inorganic Hole Transport Materials for Inverted Perovskite Solar Cells.

Organometallic halide-perovskite solar cells have undergone massive improvements in power conversion efficiency in the past decade, from around 4% in 2009 to 24% in 2019. A hotly debated issue in this field involves the investigation of economical, stable and power-efficient hole transport materials (HTMs) and electron transport materials in order to improve overall device performance and feasibility of mass production in the coming years. Even though the conventional (n-i-p) structure continues to be the most commonly used in perovskite solar cells, research in the field has shown that its potential for further commercial application is limited due to the higher J–V hysteresis and need for high temperature during fabrication. To address this issue, inverted (p-i-n) perovskite structures have been seriously examined because of their straightforward processability at low and moderate temperatures. These investigations have established that the HTMs are a significant part of the inverted (p-i-n) perovskite structure, which can render shape to a specific contact. They are perfect for reducing charge recombination and effective hole collection to enhance the overall performance of the device. This article examines in minute detail the different characteristics of inorganic hole transport materials used in inverted perovskite structures over the past decade, including power conversion efficiency, device configuration, energy band position and synthesis methods. It goes on to briefly discuss the stability analysis conducted to identify the factors which make perovskite unstable, so that possible ways to further optimize the performance parameters may be derived from the observations. [ABSTRACT FROM AUTHOR]