Recent advancements in and perspectives on flexible hybrid perovskite solar cells

Perovskite solar cells (PSCs) have attracted a great deal of attention due to their combined advantages of high efficiency and good flexibility (bendability). Here, we address the latest technology and future prospects of flexible hybrid PSCs. Flexible PSCs consist of a flexible substrate, transparent electrode, electron (or hole) conductor, perovskite, hole (or electron) conductor, and electrode layer. Among these layers, the flexible substrate and transparent electrode are critical bottlenecks for achieving high efficiency and super flexibility, since flexible polymer substrates exhibit lower transmittance than rigid glass substrates due to a higher overall refractive index and an inherently brittle transparent conducting oxide (TCO). Therefore, we mention the research background of flexible PSCs in the introduction and review their technological advancement with regard to flexible substrates and transparent electrodes in the main text. In addition, we briefly discuss the upscaling issues and the material costs of flexible PSCs for their commercialization.