the perovskite material onto transparent substrates covered with a compact TiO 2 layer and an optional mesoporous TiO 2 (or Al 2 O 3 ) scaffold layer. [34] The p-i-n structure, which involves depositing the perovskite material onto transparent substrates which are covered with an HTL, such as the poly(3,4-ethylene dioxythiophene):polystyrene sulfonic acid (PEDOT:PSS). [35] So far, PSCs based on both mesoporous and planar structure exhibit high performance and stability, however, the comparison of the advantages of two different strucutres in stability is still under debate. [36] Mesoporous Perovskite Solar CellsRecently, a new generation of photovoltaic converters, mesoporous solar cell [37] has attracted more consideration due to their low material cost, simple fabrication process, high energy conversion efficiencies, [38] like dye-sensitized solar cell, [38c] and mesoporous perovskite solar cell. [5a,21,39] PCE up to 9.7% has been achieved by using CH 3 NH 3 PbI 3 (MAPbI 3 ) perovskite nanocrystals as the light absorber to fabricate a solid-state MPSC. [21] After that the research focuses on solid-state MSCs began to transfer from DSSCs to MPSCs. [32a,40] In an MPSC, a compact layer is usually deposited on fluorine doped tin oxide (FTO) layer, which usually extracts electrons and block holes. Three strategies are broadly used for depositing the TiO 2 layer: 1) Spin-coating the colloidal dispersion of TiO 2 nanoparticles followed by a thermal treatment (titanium source: TiCl 4 , [41] titanium isopropoxide, [42] tetra-n-butyl-titanate; [43] 2) spin-coating titanium precursor solutions followed by a thermal treatment (titanium source: TiCl 4 , [44] titanium isopropoxide, [23] titanium diisopropoxide bis(acetylacetonate) 12 ); 3) spray pyrolysis deposition (titanium source: titanium diisopropoxide bis(acetylaceto nate) 18 ). [45] Low-temperature sintering approaches to prepare an

The environmental challenges across the world step up the researcher's interest in different energy resources. Semitransparent perovskite solar cells (ST-PSCs) could expedite generation of electricity as well as shows reassuring its significance in flexible electronics and building-integrating photovoltaic as so forth in the next decade. It is highly recommended to endorse the relevance of semitransparent solar devices to fulfill the required level of energy even by using the roofs and windows of the buildings. In this review article, we pay more attention to recent developments of ST-PSCs. Herein, a succinct overview of latest research about semitransparent solar cell technologies and ST-PSCs is summarized. Moreover, the strategies to enhance the transparency of solar cells are described utilizing structure, transparent electrodes, perovskite film formation, tandem solar cells, color tuning, and human eye perception. Last but not least is that the serious concerns about stability of ST-PSCs are vividly reviewed.

In recent years, the era of perovskites has experienced splendid development. Among perovskites, flexible perovskite solar cells (FPSCs) have received increasing attention due to their high efficiency, light weight, low cost, excellent flexibility, and low‐temperature solution processing ability. In the last decade, the power conversion efficiency of FPSCs has increased significantly from 2.62% to more than 20%. Herein, a succinct overview of the current endeavor to achieve low‐temperature FPSCs is provided. The recent developments, including flexible substrates, transparent conductive electrodes, perovskite absorbers, and device manufacturing methods, are vividly discussed. The strategies for enhancing the stability and flexibility of FPSCs are presented in terms of electrode materials, device encapsulation, and structural effects. Finally, the most encouraging and potential studies for the future of flexible PSCs are revealed.