Inorganic hole transport layers in inverted perovskite solar cells: A review

Abstract

In the past decades, the inverted structure (p‐i‐n structure) perovskite solar cells (PVSCs) have been attracted more by the researchers owing to their ease of fabrication, cost‐effectiveness, lower processing temperature for the fabrication of large scale and flexible devices with negligible J−V hysteresis effects. The hole transporting layer (HTL) as a major served content of PVSCs has significant influence on light harvesting, carrier extraction and transportation, perovskite crystallization, stability and cost. Generally, the organic materials are used as HTLs which have less stability due to their morphology under thermal conditions; thus, leads to change in properties of them. A tantalizing possibility is replacement of p‐type inorganic materials instead of organic materials but the plenty of options are available for inorganic HTLs. However, the development of more variants for inorganic HTL is a major challenge. Till date, many materials have been reported, but their performances have not superseded that of their organic counterparts. Herein, the review on various inorganic HTLs based inverted PVSCs has been reported and analyzed their performances with appropriate properties such as proper energy level and high carrier mobility which are not only assisted with charge transport, but also improved the stability of PVSCs under ambient conditions.