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Due to its excellent thermal stability and high performance, inorganic cesium lead mixed halide (ABX3, where A = Cs, B = Pb, and X = I/Br) all‐inorganic perovskite solar cells (IPVSCs) have attracted much interest in optoelectronic applications. However, the film quality, enough absorption by desired film thickness, and nature of partial replacement of cations determine the stability of the CsPbI2Br perovskite films. Herein, a hot air method is used to control the thickness and morphology of the CsPbI2Br perovskite thin film, and the A‐site (herein, Cs+) cation is partially incorporated by rubidium (Rb+) cations for making the stable black phase under ambient conditions. The Rb cation‐incorporated Cs1−xRbxPbI2Br (x = 0–0.03) perovskite thin films exhibit high crystallinity, uniform grains, extremely dense, and pinhole‐free morphology. The fabricated device with its Cs0.99Rb0.01PbI2Br perovskite composition with poly(3‐hexylthiophene‐2,5‐diyl) as a hole‐transporting layer exhibits a power conversion efficiency (PCE) of 17.16%, which is much higher than that of CsPbI2Br‐based IPVSCs. The fabricated Cs0.99Rb0.01PbI2Br‐based IPVSC devices retain >90% of the initial efficiency over 120 h at 65 °C thermal stress, which is much higher than that of CsPbI2Br samples.

Replacement of conventional organic cations by thermally stable inorganic cations in perovskite solar cells (PSCs) is one of the promising approaches to make thermally stable photovoltaics. However, conventional spin-coating and solvent-engineering processes in a controlled inert atmosphere hamper the upscaling. In this study, we demonstrated a dynamic hot-air (DHA) casting process to control the morphology and stability of all-inorganic PSCs which is processed under ambient conditions and free from conventional harmful antisolvents. Furthermore, CsPbI2Br perovskite was doped with barium (Ba2+) alkaline earth metal cations (BaI2:CsPbI2Br). This DHA method facilitates the formation of uniform grain and controlled crystallization that makes stable all-inorganic PSCs which enables an intact black α-phase under ambient conditions. The DHA-processed BaI2:CsPbI2Br perovskite photovoltaics shows the champion power conversion efficiency (PCE) of 14.85% (reverse scan) for a small exposure area of 0.09 cm2 and 13.78% for a large area of 1 × 1 cm2 with excellent reproducibility. Interestingly, the hot-air-processed devices retain >92% of the initial efficiency after 300 h. This DHA method facilitates a wide processing window for upscaling the all-inorganic perovskite photovoltaics.

Mixed-halide CsPbI 2 Br perovskite is promising for efficient and thermally stable all-inorganic solar cells; however, the use of conventional antisolvent methods and additives-based hole-transporting layers (HTLs) currently hampers progress. Here, we have employed hot-air-assisted perovskite deposition in ambient condition to obtain high-quality photoactive CsPbI 2 Br perovskite films and have extended stable device operation using metal cation doping and dopant-free hole-transporting materials. Density functional theory calculations are used to study the structural and optoelectronic properties of the CsPbI 2 Br perovskite when it is doped with metal cations Eu 2+ and In 3+ . We experimentally incorporated Eu 2+ and In 3+ metal ions into CsPbI 2 Br films and applied dopant-free copper(I) thiocyanate (CuSCN) and poly(3-hexylthiophene) (P3HT)-based materials as low-cost hole transporting layers, leading to record-high power conversion efficiencies of 15.27% and 15.69%, respectively, and a retention of >95% of the initial efficiency over 1600 h at 85 °C thermal stress.

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Dye-sensitized solar cells (DSSCs) have aroused great interest and been regarded as a potential renewable energy resource among the third-generation solar cell technologies to fulfill the 21 century global energy demand. DSSCs have notable advantages such as low cost, easy fabrication process and being eco-friendly in nature. The progress of DSSCs over the last 20 years has been nearly constant due to some limitations, like poor long-term stability, narrow absorption spectrum, charge carrier transportation and collection losses and poor charge transfer mechanism for regeneration of dye molecules. The main challenge for the scientific community is to improve the performance of DSSCs by using different approaches, like finding new electrode materials with suitable nanoarchitectures, dyes in composition with promising semiconductors and metal quantum dot fluorescent dyes, and cost-effective hole transporting materials (HTMs). This review focuses on DSSC photo-physics, which includes charge separation, effective transportation, collection and recombination processes. Different nanostructured materials, including metal oxides, oxide perovskites and carbon-based composites, have been studied for photoanodes, and counter electrodes, which are crucial to achieve DSSC devices with higher efficiency and better stability.

employed in order to make stable perovskite phase, which includes incorporation of inorganic cations at A-site and/or B-site with mixed halides. However, still methylammonium (MA) or formamidinium (FA) cations suffered from low thermal stability. [9][10][11] Therefore, allinorganic cesium lead halide (CsPbX 3 ) attracted tremendous attention due to its thermal stability and promising optoelectronicproperties. [12][13][14][15][16][17] Unfortunately, Cs-based all-inorganic perovskites especially CsPbI 3 are suffer from poor stability due to their thermodynamically unstable phase. The photoactive cubic alpha (α)−phase (black phase) simultaneously transforms to the orthorhombic photo inactive delta (δ)−phase (yellow phase), which is thermodynamically stable at room temperature. [12,[18][19][20][21][22][23] Therefore, it is necessary to make stable α-phase using adequate composition and deposition techniques. Several methods have been used to maintain the stable α-CsPbI 3 black phase, which includes controlled grain growth, [24] size controlling to the quantum dots (QDs), [25,26] solvent engineering process, [27] additives [18,[28][29][30] airquenching, [31,32] and metal-ion doping. [33][34][35][36][37][38][39][40][41][42][43][44][45] In case of Mn 2± doped CsPbIBr 2 , Liang et al. used Mn-doped all-inorganic perovskites having CsPb 1−x Mn x I 1+2x Br 2−2x (where x = 0.005) composition for hole transporting materials (HTMs) free (C-PSCs) and demonstrated 7.36% PCE with >300 h stability in ambient condition, which is much higher than pristine CsPbI 2 Br composition. [36] However, the dynamic hot-air process with metal ion doped CsPbI 2 Br makes stable α-phase at ambient condition. [46] Although alternative methods including postair flow, [47] coevaporation, [48] and vacuum flash [49] have been used for deposition of this CsPbX 3 layer. However, the solvent engineering process still yields the best efficiency for CsPbI 2 Br composition. [24] Thus, in the CsPbI 2 Br films, the prototypal allinorganic perovskite, the quality of the film (crystallinity and thickness), dominates the photovoltaic performance. Obtaining >1 µm grain size in the CsPbI 2 Br film by this method is easy but difficult to achieve in vertical direction and air processing The high thermal stability and facile synthesis of CsPbI 2 Br all-inorganic perovskite solar cells (AI-PSCs) have attracted tremendous attention. As far as electron-transporting layers (ETLs) are concerned, low temperature processing and reduced interfacial recombination centers through tunable energy levels determine the feasibility of the perovskite devices. Although the TiO 2 is the most popular ETL used in PSCs, its processing temperature and moderate electron mobility hamper the performance and feasibility. Herein, the highly stable, low-temperature processed MgZnO nanocrystal-based ETLs for dynamic hot-air processed Mn 2+ incorporated CsPbI2Br AI-PSCs are reported. By holding its regular planar "n-i-p" type device architecture, the MgZnO ETL and poly(3-hexylthiophene-2,5diyl) h...