This review provides a comprehensive understanding on degradation mechanisms related to intrinsic properties of perovskites and effective strategies for pushing commercialization of perovskite photovoltaic are summarized.

The hole transport material (HTM) of organic–inorganic perovskite solar cells (PVSCs) plays a very important role for achieving high power conversion efficiency and long‐term stability. 2,2’,7,7’‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9‐9’‐spirobifluorene (spiro‐OMeTAD) is the first solid‐state HTM used in PVSCs and has gained tremendous attention during the last decade. Herein, the concept of spirolinkage for synthesis of spiro‐based HTMs is discussed, followed by an overview of the desirable optical and electrical properties of spiro‐OMeTAD. Recent progress in efficiency improvements of spiro‐based PVSCs is analyzed systematically, and the impacts of interface engineering, dopant‐free spiro‐OMeTAD, and novel spiro‐based HTMs are reviewed in detail. The hole mobility of spiro‐OMeTAD depends on the types of dopants and doping concentration. Commonly used lithium bis(trifluoromethylsulfonyl)imide and 4‐tert‐butylpyridine additives reduce the PVSC stability due to hygroscopicity and corrosiveness, respectively. The effects of additives on device stability and the techniques to improve the long‐term stability of spiro‐based PVSCs are also discussed. The review and analysis of various methods and strategies presented is useful for the perovskite research community, providing guidance and directions toward the further development of spiro‐based HTMs for PVSCs with improved efficiency and stability.

The world record device efficiency of single‐junction solar cells based on organic–inorganic hybrid perovskites has reached 25.5%. Further improvement in device power conversion efficiency (PCE) can be achieved by either optimizing perovskite films or designing novel device structures such as perovskite/Si tandem solar cells. With the marriage of perovskite and Si solar cells, a tandem device configuration is able to achieve a PCE exceeding the Shockley–Queisser limit of single‐junction solar cells by enhancing the usage of solar spectrum. After several years of development, the highest PCE of the perovskite/Si tandem cell has reached 29.5%, which is higher than that of perovskite‐ and Si‐based single‐junction cells. Here, in this review, we will (1) first discuss the device structure and fundamental working principle of both two‐terminal (2T) and four‐terminal (4T) perovskite/Si tandem solar cells; (2) second, provide a brief overview of the advances of perovskite/Si tandem solar cells regarding the development of interconnection layer, perovskite active layer, tandem device structure, and light management strategies; (3) third, discuss the challenges and opportunities for further developing perovskite/Si tandem solar cells. This review article, on the one hand, provides a comprehensive understanding to readers on the development of perovskite/Si tandems. On the other hand, it proposes various novel applications that may bring such tandems into the market in a near future.