Organic–inorganic hybrid perovskite solar cells (PSCs) are currently attracting significant interest owing to their promising outdoor performance. However, the ability of indoor light harvesting of the perovskites and corresponding device performance are rarely reported. Here, the potential of planar PSCs in harvesting indoor light for low‐power consumption devices is investigated. Ionic liquid of 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM]BF4) is employed as a modification layer of [6,6]‐phenyl‐C61‐butyric acid methyl ester) (PCBM) in the inverted PSCs. The incorporation of [BMIM]BF4 not only paves the interface contact between PCBM and electrode, but also facilitates the electron transport and extraction owing to the efficient passivation of the surface trap states. Moreover, [BMIM]BF4 with excellent thermal stability can act as a protective layer by preventing the erosion of moisture and oxygen into the perovskite layer. The resulting devices present a record indoor power conversion efficiency (PCE) of 35.20% under fluorescent lamps of 1000 lux, and an impressive PCE of 19.30% under 1 sun illumination. The finding in this work verifies the excellent indoor performance of PSCs to meet the requirements of eco‐friendly economy.

With the efforts of researchers from all over the world, metal halide perovskite solar cells (PSCs) have been booming rapidly in recent years. Generally, perovskite films are sensitive to surrounding conditions and will be changed under the action of physical fields, resulting in lattice distortion, degradation, ion migration, and so on. In this review, the progress of physical fields manipulation in PSCs, including the electric field, magnetic field, light field, stress field, and thermal field are reviewed. On this basis, the influences of these fields on PSCs are summarized and prospected. Finally, challenges and prospective research directions on how to make better use of external-fields while minimizing the unnecessary and disruptive impacts on commercial PSCs with high-efficiency and steady output are proposed.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.202107556. IntroductionRecent years, metal halide perovskite solar cells (PSCs) have attracted widespread attention, and their power conversion efficiency (PCE) has been rapidly increased by more than 25%. [1] In order to obtain highly efficient photovoltaic devices, the fabrication process, the photoelectric properties of perovskite active layer, the interface contact, the electrode conductivity, and so on are all crucial. Researchers have made a lot of attempts, such as, adding dopants into the perovskite film to assist the crystallization, [2] adjusting the chemical composition of the perovskite layer to regulate its bandgap, [3] changing the preparation processes and conditions to improve the crystal quality, [4] designing