- Award ID(s):
- Publication Date:
- NSF-PAR ID:
- Journal Name:
- Journal of Materials Chemistry A
- Page Range or eLocation-ID:
- 234 to 244
- Sponsoring Org:
- National Science Foundation
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The past decade has witnessed tremendous advances in synthesis of metal halide perovskites and their use for a rich variety of optoelectronics applications. Metal halide perovskite has the general formula ABX 3 , where A is a monovalent cation (which can be either organic ( e.g. , CH 3 NH 3 + (MA), CH(NH 2 ) 2 + (FA)) or inorganic ( e.g. , Cs + )), B is a divalent metal cation (usually Pb 2+ ), and X is a halogen anion (Cl − , Br − , I − ). Particularly, the photoluminescence (PL) properties of metal halide perovskites have garnered much attention due to the recent rapid development of perovskite nanocrystals. The introduction of capping ligands enables the synthesis of colloidal perovskite nanocrystals which offer new insight into dimension-dependent physical properties compared to their bulk counterparts. It is notable that doping and ion substitution represent effective strategies for tailoring the optoelectronic properties ( e.g. , absorption band gap, PL emission, and quantum yield (QY)) and stabilities of perovskite nanocrystals. The doping and ion substitution processes can be performed during or after the synthesis of colloidal nanocrystals by incorporating new A′, B′, or X′ site ions into themore »
Impact of cesium on the phase and device stability of triple cation Pb–Sn double halide perovskite films and solar cellsTriple cation Cs/methylammonium (MA)/formamidinium (FA) and double halide Br/I lead perovskites improved the stability and efficiency of perovskite solar cells (PVSCs). However, their effects on alloyed Pb–Sn perovskites are unexplored. In this work, perovskite thin films with the composition Cs x (MA 0.17 FA 0.83 ) 1−x Pb 1−y Sn y (I 0.83 Br 0.17 ) 3 are synthesized utilizing a one-step solution process plus an anti-solvent wash technique and deployed in PVSCs with an inverted architecture. All films show a cubic crystal structure, demonstrating that compositional tuning of both the tolerance factor and crystallization rate allows for dense, single phase formation. The band gaps, affected by both lattice constriction and octahedral tilting, show opposite trends in Pb-rich or Sn-rich perovskites with the increase of Cs for fixed Sn compositions. The Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb 0.25 Sn 0.75 (I 0.83 Br 0.17 ) 3 PVSCs achieve a power conversion efficiency (PCE) of 11.05%, a record for any PVSC containing 75% Sn perovskites, and the Cs 0.10 (MA 0.17 FA 0.83 ) 0.90 Pb 0.75 Sn 0.25 (I 0.83 Br 0.17 ) 3 PVSCs reach a record PCE of 15.78%. Moreover, the triple cation and doublemore »
Tunable optical properties and stability of lead free all inorganic perovskites (Cs 2 SnI x Cl 6−x )Organic–inorganic hybrid lead-based perovskites experience significant environmental instability under ambient moist air and are not environmentally benign due to the usage of toxic Pb. Here, we report a new approach to synthesize lead-free all inorganic perovskites (Cs 2 SnI x Cl 6−x ) using hydriodic acid (HI) demonstrating greatly enhanced environmental stability and tunable optical properties by controlling the I − /Cl − ratios. Single phase perovskites can be achieved with a low iodine or chlorine content, and a phase separation occurs in the binary system with closer iodine and chlorine dopings. UV-vis diffuse reflectance and photoluminescence measurements reveal tunable band gaps of Cs 2 SnI x Cl 6−x perovskites from the UV to the infrared region. The mixed halide perovskite with a lower chloride content shows significantly higher photoluminescence intensity. The thermal stability of mixed halide all-inorganic perovskites is continuously improved as the Cl content increases. The synthesis of Sn-based perovskites with tunable optical properties and environmental stability represents one step further toward the realization of the stable lead-free all inorganic perovskites.
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