Advances in Processing Kinetics for All‐Inorganic Halide Perovskite: Towards Efficient and Thermodynamic Stable Solar Cells

Abstract

path of perovskite solar cells (PSCs). [2] A major reason for perovskite instability is the presence of organic cation CH 3 NH 3 + (MA + ) and HC(NH 2 ) 2 (FA + ) which are hygroscopic and volatile. [3] An effective approach to fight the thermal instability is the replacement of an organic cation with an inorganic cation. Within the perovskite composition space, cesium (Cs + ) is the only inorganic cation that can successfully crystallize in the cubic perovskite phase. [4,5] Cahen with co-workers 2015 established that all-inorganic perovskites have the potential to work equally well as hybrid perovskites and can provide better stability. [6,7] An extensive work was hereafter done by researchers on CsPbX 3 leading to its emergence as a rising star of photovoltaics. Interestingly, CsPbX 3 perovskite exists in different phases depending on temperature, synthesizing conditions, and composition. [8,9] Among the different halogen counterparts of CsPbX 3 , the iodine counterpart exhibits the most suitable optical bandgap (1.7 eV) for solar cells per Shockley-Queisser (SQ) limit. Owing to the rigorous work including doping, alloying, and interface engineering, CsPbX 3 showed an outstanding enhancement in power conversion efficiency (PCE) from 5.72% in 2015 to 20.7% in 2021. [6,10] Also, the other halogen counterparts are studied for low-temperature crystallization and stabilization. Apart from single-junction solar cells, research in the next generation of PSCs is also focusing on the formation of tandem solar cells (TSCs). TSCs are utilizing wide-bandgap semiconductors as front cells and narrow-bandgap semiconductors as rear cells to absorb high and low-energy photons, respectively. The bandgap of CsPbX 3 is quite suitable to serve as the front cell in TSCs with another low-bandgap perovskite, silicon, organic semiconductor blends, and CIGS as the rear cell. [11] Cao et al. proposed using inorganic perovskites in conjunction with organic semiconductors. [12] Recently, Wang et al. successfully utilized a wide-bandgap CsP-bI 2 Br semiconductor and an organic blend of narrow-bandgap PM6:Y6-BO to fabricate perovskite/organic tandem solar cells which yielded an efficiency of 21.1%. [13] Although thermally stable, CsPbI 3 faces the problem of moisture instability and high-temperature crystallization. This instability is attributed to the small ionic radii of Cs (167 pm) which result in a Goldschmidt tolerance value of 0.81. [14] The all-inorganic CsPbX 3 (X-Cl, Br, I) perovskite has the potential to solve the practical issues of environmental instability due to the presence of hygroscopic organic cations in the hybrid organic-inorganic perovskites. The promising CsPbX 3 perovskite exists in different crystallographic phases depending upon the composition and processing conditions which potentially impact the film morphology, device efficiency, and stability. Stabilizing the black metastable phase at room temperature has substantially solved the problem of high crystallization temperature, which is the main roadblock in managi...

Organic–Inorganic Hybrid Cuprous‐Based Metal Halides for Warm White Light‐Emitting Diodes

“…It is noted that size of the obtained single crystals can be increased even further by using a bigger scintillation vial, significantly larger than most of the other Pb‐free perovskites. [ 25–28 ] The large‐scale uniform rod morphology lays the foundation for the design of centimeter‐level single‐crystal devices. [ 28,29 ] It is important to note that the successful application of this method for crystallization depends on the use of H 3 PO 2 , which was added to prevent the oxidation of Cu + , [ 17 ] otherwise nonluminescent Cu 2+ ‐contained compounds can be produced (Figure S1, Supporting Information).…”

Optical Memory, Switching, and Neuromorphic Functionality in Metal Halide Perovskite Materials and Devices

“…However, optical memory, switching and neuromorphic functionality may not require the same optoelectronic features that distinguish Pb‐based compounds from their alternatives in the PV realm. There are now many examples of optical switching behavior in Cu‐, [ 233–236 ] Bi‐, [ 237 ] Sb‐halide, [ 238,239 ] and double perovskite compounds [ 240 ] (such as Cs 2 AgBiBr 6 ) that feature two metal centers. [ 241,242 ] Each of these metal centers has multiple stable oxidations states, which points to the likelihood of an even richer diversity of switching chemistries compared to the Pb‐halide system reviewed here that tend toward Pb 0 or Pb 2+ states.…”

Recent Progress of Film Fabrication Process for Carbon-Based All-Inorganic Perovskite Solar Cells

“…Up to date, C-IPSCs have shown high stability, while performance is still far below their Shockley-Queisser limit [35]. For instance, the top level PCE of CsPbI 3 -based devices reported so far is about 15%, which is only 50% of the Shockley-Queisser limit [36][37][38]. In order to increase the progress of large-scale commercialization of C-IPSCs, it is necessary to overcome the obstacles, such as further enhancement of PCE of C-IPSCs, decreasing energy level difference at the interfaces for more efficient carrier transport, and improvement of phase stability of the all-inorganic perovskite films.…”