Air‐stable p‐type SnF2:Cs2SnI6with a bandgap of 1.6 eV has been demonstrated as a promising material for Pb‐free halide perovskite solar cells. Crystalline Cs2SnI6phase is obtained with CsI, SnI2, and SnF2salts in gamma‐butyrolactone solvent, but not with dimethyl sulfoxide and
Cs2SnI6perovskite displays excellent air stability and a high absorption coefficient, promising for photovoltaic and optoelectronic applications. However, Cs2SnI6‐based device performance is still low as a result of lacking optimized synthesis approaches to obtain high quality Cs2SnI6crystals. Here, a new simple method to synthesize single crystalline Cs2SnI6perovskite at a liquid–liquid interface is reported. By controlling solvent conditions and Cs2SnI6supersaturation at the liquid–liquid interface, Cs2SnI6crystals can be obtained from 3D to 2D growth with controlled geometries such as octahedron, pyramid, hexagon, and triangular nanosheets. The formation mechanisms and kinetics of complex shapes/geometries of high quality Cs2SnI6crystals are investigated. Freestanding single crystalline 2D nanosheets can be fabricated as thin as 25 nm, and the lateral size can be controlled up to sub‐millimeter regime. Electronic property of the high quality Cs2SnI62D nanosheets is also characterized, featuring a n‐type conduction with a high carrier mobility of 35 cm2V−1s−1. The interfacial reaction‐controlled synthesis of high‐quality crystals and mechanistic understanding of the crystal growth allow to realize rational design of materials, and the manipulation of crystal growth can be beneficial to achieve desired properties for potential functional applications.
more » « less- NSF-PAR ID:
- 10454440
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Small
- Volume:
- 17
- Issue:
- 4
- ISSN:
- 1613-6810
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
N,N ‐dimethylformamide solvents. Cs2SnI6is found to be stable for at least 1000 h at 100 °C when dark annealed in nitrogen atmosphere. In this study, Cs2SnI6has been used in a superstrate n–i–p planar device structure enabled by a spin‐coated absorber thickness of ≈2 μm on a chemical bath deposited Zn(O,S) electron transport layer. The best device power conversion efficiency reported here is 5.18% withV OCof 0.81 V, 9.28 mA cm−2J SC, and 68% fill factor. The dark saturation current and diode ideality factor are estimated as 1.5 × 10−3 mA cm−2and 2.18, respectively. The devices exhibit a highV OCdeficit and low short‐circuit current density due to high bulk and interface recombination. Device efficiency can be expected to increase with improvement in material and interface quality, charge transport, and device engineering. -
more » « less
Abstract Organic–inorganic hybrid perovskites have emerged as promising optoelectronic materials for applications in photovoltaic and optoelectronic devices. Particularly, 2D layer‐structured hybrid perovskites are of great interest due to their remarkable optical and electrical properties, which can be easily tuned by selecting suitable organic and inorganic moieties during the material synthesis. Here, the solution‐phase growth of a large square‐shaped single‐crystalline 2D hybrid perovskite, phenethylammonium lead bromide (C6H5C2H4NH3)2PbBr4(PEPB), with thickness as few as 3 unit cell layers is demonstrated. Compared to bulk crystals, the 2D PEPB nanocrystals show a major blueshifted photoluminescence (PL) peak at 409 nm indicating an increase in bandgap of 40 meV. Besides the major peak, two new PL peaks located at 480 and 525 nm are observed from the hybrid perovskite nanocrystals. PEPB nanocrystals with different thicknesses show different colors, which can be used to estimate the thickness of the nanocrystals. Time‐resolved reflectance spectroscopy is used to investigate the exciton dynamics, which exhibits a biexponential decay with an amplitude‐weighted lifetime of 16.7 ps. The high‐quality 2D (C6H5C2H4NH3)2PbBr4nanocrystals are expected to have high PL quantum efficiency and potential applications for light‐emitting devices.
-
more » « less
Abstract Room temperature semiconductor detector (RTSD) materials for γ‐ray and X‐ray radiation are in great demand for the nonproliferation of nuclear materials as well as for biomedical imaging applications. Halide perovskites have attracted great attention as emerging and promising RTSD materials. In this contribution, the material synthesis, purification, crystal growth, crystal structure, photoluminescence properties, ionizing radiation detection performance, and electronic structure of the inorganic halide perovskitoid compound TlPbI3are reported on. This compound crystallizes in the ABX3non‐perovskite crystal structure with a high density of
d = 6.488 g·cm–3, has a wide bandgap of 2.25 eV, and melts congruently at a low temperature of 360 °C without phase transitions, which allows for facile growth of high quality crystals with few thermally‐activated defects. High‐quality TlPbI3single crystals of centimeter‐size are grown using the vertical Bridgman method using purified raw materials. A high electrical resistivity of ≈1012 Ω·cm is readily obtainable, and detectors made of TlPbI3single crystals are highly photoresponsive to Ag KαX‐rays (22.4 keV), and detects 122 keV γ‐rays from57Co radiation source. The electron mobility‐lifetime productµeτe was estimated at 1.8 × 10–5cm2·V–1. A high relative static dielectric constant of 35.0 indicates strong capability in screening carrier scattering and charged defects in TlPbI3. -
more » « less
Abstract A novel low‐temperature route is developed for inkjet printing of the perovskite Cs2SnI6, to create wearable negative‐temperature‐coefficient thermistors with unprecedented performance on thermally sensitive fabrics. A low processing temperature of 120 °C is achieved by creating a stable and printable ink using binary metal iodide salts, which is thermally transformed into dense Cs2SnI6crystals after printing. The optimally printed Cs2SnI6shows a temperature measurement range up to 120 °C, high sensitivity (4400 K), and temperature coefficient of resistivity (0.05 °C−1), and stability under ambient environmental conditions and bending. The approach breaks a critical tradeoff that has hindered wearable fabric‐based thermistors by enabling damage‐free fabrication of devices with commercially comparable performance, evincing significant applications in multifunctional textiles and beyond.
-
more » « less
Chalcogenide perovskites are promising semiconductor materials with attractive optoelectronic properties and appreciable stability, making them enticing candidates for photovoltaics and related electronic applications. Traditional synthesis methods for these materials have long suffered from high‐temperature requirements of 800–1000 °C. However, the recently developed solution processing route provides a way to circumvent this. By utilizing barium thiolate and ZrH2, this method is capable of synthesizing BaZrS3perovskite at modest temperatures (500–600 °C), generating crystalline domains on the order of hundreds of nanometers in size. Herein, a systematic study of this solution processing route is done to gain a mechanistic understanding of the process and to supplement the development of device quality fabrication methodologies. A barium polysulfide liquid flux is identified as playing a key role in the rapid synthesis of large‐grain BaZrS3perovskite at modest temperatures. Additionally, this mechanism is successfully extended to the related BaHfS3perovskite. The reported findings identify viable precursors, key temperature regimes, and reaction conditions that are likely to enable the large‐grain chalcogenide perovskite growth, essential toward the formation of device‐quality thin films.
