Methylammonium and Bromide‐Free Tin‐Based Low Bandgap Perovskite Solar Cells

Abstract

its volatility and reversible/irreversible decomposition reaction even at low temperature, MA is gradually avoided in the material designs. [9] At the same time, FA is more thermally stable than MA due to its stronger hydrogen bonding with PbX 6 octahedra and benign reversible decomposition reaction below 85 °C, and it is the primary cation in practically all current high-performance PSCs. [10,11] Also, FA has no irreversible (nonselective) back reaction. [12] At the same time, in order to approach the bandgap of 1.34 eV according to the Schottky-Queisser (S-Q) limit, from initially MAPbI 3 to double cation (MAFA or FACs), [10,13,14] triple cation (CsMAFA) based perovskites, [5] eventually to quadruple (CsRbMAFA) based perovskites, [4,[15][16][17] and recently FAPbI 3 are dominated ones. [18][19][20] FAPbI 3 has an ideal, narrow bandgap since FA remains the largest organic cation that fits into a 3D perovskite crystal structure. [21] The implicit or explicit goal of perovskite research is to obtain a black FA-based (stable phase) perovskite at room temperature. Avoiding yellow phase impurities encouraged the advancement of processing techniques and elaborate multication, multi-halide mixtures.It has been proved that the invasion of Br anion at the X site is effective for stabilizing the black phase FA-based and other perovskites. But it leads to an adverse blue-shift of the bandgap disproportionately. For example, there is a spanning of 700 meV persisting in MAPbI x Br 1-x from 2.28 eV (MAPbBr 3 ) to 1.58 eV (MAPbI 3 ). [22] Furthermore, from a stability perspective, introducing Br anion in iodide-based perovskites is unfavorable since Br/I mixtures will undergo severe anion segregation Lead halide-based perovskite solar cells (PSCs) are intriguing candidates for photovoltaic technology because of their high efficiency, low cost, and simple process advantages. Owing to lead toxicity, PSCs based on partially/fully substituted Pb with tin have attracted tremendous attention, which would enable the ideal bandgap to approach the Shockley-Queisser (S-Q) limit. Especially, methylammonium (MA), bromide-free, tin-based perovskites are striking, because of the intrinsic poor stability of MA and blue shift caused by the incorporation of Br − . The first section of this review emphasizes the motivation for studying single-junction MA, Br-free, and Sn-based perovskites. The film quality improvement strategies of Sn-based perovskites, including additive, composition, dimensional, and interface engineering toward high-efficiency devices are comprehensively overviewed. Moreover, strategies to improve stability, where shelf, thermal and operational stabilities of the devices are summarized. Finally, this review concludes with a discussion of actual limitations and future prospects for Sn-based PSCs.

Highly efficient and stable Cs2TeCl6:Cr3+ perovskite microcrystals for white light emitting diodes

“…In recent years, some non-or less-toxic alternatives, such as bismuth (Bi), tin (Sn), antimony (Sb), and tellurium (Te), for substituting Pb (II) have been developed and proposed. [6][7][8] Among diverse candidates, Te (IV) was found to be a nonmetallic element with the strongest metallic properties. Te (IV)-based lead-free perovskites have low toxicity, high stability (DH = À1.35 eV), 9 large absorption crosssections, and broadband yellow light emission, demonstrating potential value for lighting applications.…”

Sn‐Based Perovskite Halides for Electronic Devices

“…[20] The rapid development in THP-based optoelectronics devices makes it urgently necessary to review and assess their potential for several optoelectronic and electronic applications. In this regard, earlier published reviews have highlighted the progress and potential of THP's applications with solar cells, [29][30][31][32] photodetectors, [33] light-emitting devices, and radiation detectors. [34] With intense research for various applications, THP-based electronic devices show encouraging performances.…”

Improved Structural Order and Exciton Delocalization in High-Member Quasi-Two-Dimensional Tin Halide Perovskite Revealed by Electroabsorption Spectroscopy

“…Besides their low toxicity, tin perovskites have also been predicted to exhibit excellent optoelectronic properties for solar cells, such as an ideal solar cell bandgap and high carrier mobility. , However, Sn 2+ in bulk tin perovskites is generally susceptible to oxidation, which leads to a high defect density within the photoactive layer that greatly limits the solar cell efficiency (below 10% before 2020) . Since then, significant efforts have been made by the research community to improve the performance of tin perovskite solar cells by approaches including chemical composition engineering, manipulation of crystallization kinetics, suppression of Sn 2+ oxidation with a reducing reagent, and surface passivation. − …”