The present invention generally relates to the field of photodetectors. More specifically, the present invention relates to a photodetector with enhanced performance, based on 2D bilayered hybrid lead halide perovskite single crystal with ACI phase.
Photodetectors (PDs), which can directly convert optical signals into electrical signals, play a significant part in imaging, security systems, industrial inspection, and so on. To fabricate high-performance PDs, a semiconductor with a good ability to absorb incident photons and then produce photogenerated carriers effectively is indispensable. So far, various types of semiconductors, including silicon, group II-VI compounds, group III-V compounds, and organics, have been extensively explored for use in PDs.
However, these semiconductor materials usually require relatively complicated and expensive ways to synthesize, in which the epitaxy and vapor-liquid-solid (VLS) mechanisms are usually involved. Thus, it is urgent to discover new promising candidates to further design the photodetector with high performance, low cost, and case of fabrication.
Recently, the three-dimensional (3D) organic-inorganic hybrid lead halide perovskites in the forms of CH3NH3PbX3 (X=I, Br, Cl) have received intense attention owing to their low-cost fabrication and excellent optoelectronic properties. As a result, they have impressive developments, especially in the high-efficient perovskite solar cells. To date, a certified photovoltaic power conversion efficiency (PCE) of hybrid perovskite solar cells has approached 25.7% (until March. 2023), which is higher than that of many reported conventional thin-film solar cells, organic photovoltaics, and dye-sensitized solar cells.
Moreover, this kind of material with excellent features has also attracted enormous attention in other optoelectronic devices, such as lasers, transistors, and light-emitting diodes (LEDs). Especially, perovskites have been examined for high-performance wide-spectrum photodetection from X-ray, UV, visible, to near-infrared light. However, the poor stability of these 3D perovskite-based devices hinders their further commercial applications.
Using short alkyl ammonium or aromatic ammonium cations to low-dimensional perovskites is an effective method to balance device stability and performance. Based on this route, plenty of perovskites with different dimensions, including zero-dimension (OD), one-dimension (1D), and two-dimension (2D), were synthesized. Among them, 2D perovskite shows better optoelectronic performance when compared with OD and ID perovskite due to their layered structure being analogue to the conventional 3D perovskites.
From a structural perspective, 2D layered hybrid perovskites could be classified into three types: Dion-Jacobson (DJ), Ruddlesden-Popper (RP), and the newly discovered alternating cations in the interlayer (ACI) types. The 2D ACI perovskite described by the formula (C(NH2)3) (CH3NH3)nPbnI3n+1, featuring two different alternating organic cations in the interlayer space, was recently presented.
Compared to the more common DJ-phase and RP-phase layered hybrid perovskites, the perovskite with ACI phase adopts the short organic cations between inorganic layers, which decrease the bandgap and exciton binding energy, being favorable for the performance improvement of optoelectronic devices. For example, a stable 2D ACI perovskite solar cells is reported with superior PCE exceeding 19.00%. In addition, a LED made of the ACI perovskites was successfully fabricated, showing an external quantum efficiency (EQE) of 3.4% under high current density. In this regard, the 2D hybrid perovskites with ACI phase possess great potential for manufacturing high-performance photodetection with improved stability.
In view of the immense potential in the use of two-dimensional hybrid perovskites with ACI phase for high-performance photodetection, the present invention discloses a facile and cost-efficient method of synthesizing a novel 2D bilayered lead-halide hybrid perovskite single crystals with ACI phase, which has a chemical formula of GAMA2Pb2I7, where GA is C(NH2)3 and MA is CH3NH3, based on a cooling crystallization method.
In accordance with a first aspect of the present invention, the method of synthesizing the two-dimensional lead-halide hybrid perovskites perovskite single crystals comprises adding a guanidine salt, a methylamine component and a lead salt into a solution of hypophosphorous acid (H3PO2) water solution and hydroiodic acid (HI). The mixture is subsequently heated to a temperature of 220° C. to 240° C. and stirring to remove all precipitation, stirred to remove all precipitation, and cooled to a room temperature of 15° C. to 25° C., where the saturated solution is cooled and desired crystals are formed by crystallization and obtained, with a yield of at least 70% relative to Pb.
In one embodiment of the first aspect of the invention, the guanidine salt is selected from guanidine carbonate, guanidine hydrochloride, guanidinium bromide, guanidinium iodide or guanidine phosphate, or any combinations thereof.
In another embodiment, the methylamine component is selected methylamine, methylamine hydrochloride, methylammonium bromide, or any combinations thereof.
In other embodiment, the lead salt is selected from lead carbonate, lead iodide, lead bromide, lead chloride, lead (II) acetate trihydrate, or any combinations thereof.
In an embodiment of the first aspect of the invention, the molar ratio of guanidine salt, lead salt and methylamine component is selected from a range of 1:1.5:1.5 to 1:2.5:2.5.
In another embodiment, the speed of cooling the mixture from a temperature of 65° C. to 85° C. to room temperature of 15° C. to 25° C. is 0.5° C./day to 2° C./day.
A photodetection device is also provided herewith, comprising the 2D bilayered lead-halide hybrid perovskite single crystals of GAMA2Pb2I7, disposed on a substrate and having electrodes formed thereon.
In an embodiment of the second aspect of the invention, the electrodes are deposited on the two-dimensional bi-layered lead-halide hybrid perovskite single crystals with ACI phase by a high-vacuum thermal evaporator at a thickness of 45 nm to 55 nm.
In a further embodiment, the electrodes comprise gold (Au).
In other embodiment, the substrate is selected from glass, ceramic, polymer, semiconductor or any combination thereof.
In another embodiment, the photoresponsivity of the device is at least 1.50 A/W under an incident light with a wavelength of 400 nm to 700 nm.
In yet another embodiment, the detectivity of the device is at least 1.50×1012 Jones under an incident light with a wavelength of 400 nm to 700 nm.
The present invention provides a method of synthesizing a novel two-dimensional bi-layered lead-halide hybrid perovskite single crystals with ACI phase, wherein the chemical formula of the two-dimensional bi-layered lead-halide hybrid perovskite single crystals with ACI phase is GAMA2Pb2I7, (where GA is C(NH2)3 and MA is CH3NH3). The two-dimensional bi-layered lead-halide hybrid perovskite single crystals with ACI phase display higher crystal symmetry and narrowed bandgaps, which has a great potential in significant enhancement in photodetection performance.
ACI-phase perovskites have the formula R′AnBnX3n+1, where the smaller cation R also fills the interlayer with another bulky ‘R’ cation. Most ACI-phase perovskites are formed by incorporating guanidinium (GUA+) and MA+ cations. The ACI-phase perovskite has an unprecedented structure that can be viewed as blending the chemical formula of the RP-phase perovskite with the structural features of the DJ-phase perovskite. Compared with the common RP-phase perovskites, ACI-phase perovskites have a different stacking motif and adopt a higher crystal symmetry, with a slightly narrower bandgap. As direct bandgap semiconductors are with wide valence and conduction bandwidths, ACI-phase perovskites show promising potential for photovoltaic applications.
Specifically, the synthesis method is based on cooling crystallization, which is highly facile in comparison with other existing 2D perovskite crystal synthesis methods, while maintaining a reasonably high yield of no lower than 70% in relation to Pb.
In addition, a photodetection device comprising the novel two-dimensional bi-layered lead-halide hybrid perovskite single crystals with ACI phase is also disclosed herewith, with a structure of Au/GAMA2Pb2I7/Au, which exhibits high photoresponsivity and high detectivity values under incident light of wavelengths within the spectrum of visible light, i.e. approximately 400 nm-700 nm.
As the synthesis method of the novel two-dimensional bi-layered lead-halide hybrid perovskite single crystals with ACI phase could be performed with relatively low-cost apparatuses without the requirement of specific or harsh conditions, facile and cost-effective production of the photodetection device is possible.
In accordance with a first aspect of the present invention, the synthesis method involves adding guanidine carbonate salt (GA), methylamine hydrochloride (MA), and lead (II) acetate trihydrate into a solution containing hypophosphorous acid (H3PO2) and hydroiodic acid (HI). The resulting mixture undergoes heating to a temperature between 220° C. and 240° C., with continuous stirring to remove all precipitants. Subsequently, the mixture is cooled to room temperature (for example, a temperature range of approximately 15° C. to 25° C.) to obtain the crystallized products. The two-dimensional bi-layered lead-halide hybrid perovskite single crystals with ACI phase, denoted as GAMA2Pb2I7, are formed, where GA represents C(NH2)3 and MA represents CH3NH3. The yield of these crystals with ACI phase is guaranteed to be at least 70% relative to lead (Pb).
A molar ratio of guanidine carbonate salt, lead (II) acetate trihydrate, and methylamine hydrochloride, may be within a range of 1:1.5:1.5 to 1:2.5:2.5 to optimize the synthesis process.
The cooling process involves a controlled speed from 65° C. to room temperature (15° C. to 25° C.) at 1° C./day, ensuring the gradual formation of the desired crystal structure.
The photodetector of
The photodetector of
The 2D hybrid perovskite of GAMA2Pb2I7 crystals was synthesized using guanidine carbonate salt (C2H10N6·CH2O3, 99%, J&K Scientific), lead (II) acetate trihydrate (C4H6O4Pb·3H2O, 99%, Sigma-Aldrich), methylamine hydrochloride (CH5N·HCl, 99%, J&K Scientific), hypophosphorous acid (H3PO2, 50% (in mass) water solution, J&K Scientific) and hydroiodic acid (HI, 47%, Macklin). First, 5.4 g (59.5 mmol) guanidine carbonate salt, 4.02 g (30.0 mmol) methylamine hydrochloride, and 22.8 g (60.1 mmol) lead (II) acetate trihydrate were slowly added into a solution of 100 mL hydroiodic acid and 2 mL hypophosphorous acid. After that, a quick stir would mix them thoroughly at a temperature of 230° C. until there is no precipitation. The small GAMA2Pb2I7 powder-like samples would appear when cooling to room temperature (20° C./h) as crystallized products. A yield of 76% was estimated relative to Pb. To allow the growth of crystallized products into the form of bulk perovskite crystals, a constant-speed temperature-programmable bath was used to control the cooling speed. After cooling the bath from 65° C. to room temperature (1° C./d), millimeter-level bulk crystals were obtained (see
To fabricate the photodetection device, Au electrodes with a thickness of 50 nm were deposited by a high-vacuum thermal evaporator with an evaporation rate of about 1.8 Å/s. In a shadow masking process, the length and width of the device channel were defined to be 65 μm and 15 μm, respectively. Room temperature I-V and I-T characteristics under different incident light wavelengths (405, 532, and 635 nm) were measured using a semiconductor analyzer (Agilent 4155C). The incident light power was calibrated by PM400, Thorlabs. To obtain the high-speed response time, precisely time-resolved I-T curves of the GAMA2Pb2I7 device were recorded via a digital oscilloscope (Tektronix, TBS 1102B,) connected with a low-noise current preamplifier (Stanford Rescarch Systems, SR570).
As the photograph shown in
As the ultraviolet-visible absorption spectrum shown in
Based on the good material properties, single-crystal GAMA2Pb2I7 photodetectors were constructed using Au as electrodes and glass as a substrate, where the planar device configuration is shown in
First, the spectral response of single-crystal GAMA2Pb2I7 was measured with wavelength ranging from 400 nm to 800 nm under an applied voltage of −1.5 V bias (
At the same time, the I-T curves of the GAMA2Pb2I7 PDs were also recorded under different illumination of 405 nm, 532 nm, and 635 nm laser at −1.5 V (
To understand the photoresponse behaviors, the incident light power versus photocurrent Iph (Iph=Ion−Idark) is compiled under the illumination of different wavelength light (
where P represents the photocurrent, while x and A mean the fitting exponent and the scaling constant, respectively. Through fitting, the Iph shows a power dependence of 0.86, 0.81, and 0.70 under 405, 532, and 635 nm incident light. Such sublinear correlation between the Iph and the incident light intensity can be attributed to the intricate mechanisms involving exciton generation, trapping, and recombination, which are commonly witnessed in semiconducting materials.
Besides, to further evaluate the photodetection performance of the GAMA2Pb2I7 photodetector, the responsivity (R), detectivity (D*), and EQE were obtained by the following formulas:
where S is the active area of the photodetector, q is the absolute value of electron charge (1.6×10−19 C), Idark represents the dark current, h represents the Planck's constant, c means the velocity of light, and λ represents the incident wavelength. The light intensity-dependent R of the device under illumination with different light intensities were measured, as depicted in
8.1 × 108
Furthermore, the D* and EQE under different light intensities were calculated and shown in
Moreover, the stability of organic-inorganic hybrid perovskite is essential for practical application.
The thermogravimetric analysis curve also shows high thermal stability up to 260° C. (
Based on the outstanding photosensitivity in the visible light region, the GAMA2Pb2I7 photodetector holds excellent potential for imaging applications. Herein, a high-resolution imaging system is built based on the GAMA2Pb2I7 photodetector. As shown in
It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application.
All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.
It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One having ordinary skill in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details or practiced with other methods, protocols, reagents, cell lines and animals. The present invention is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Furthermore, not all illustrated acts, steps or events are required to implement a methodology in accordance with the present invention. Many of the techniques and procedures described, or referenced herein, are well understood and commonly employed using conventional methodology by those skilled in the art.
Unless otherwise defined, all terms of art, notations and other scientific terms or terminology used herein are intended to have the meanings commonly understood by those of skill in the art to which this invention pertains. In some cases, terms with commonly understood meanings are defined herein for clarity and/or for ready reference, and the inclusion of such definitions herein should not necessarily be construed to represent a substantial difference over what is generally understood in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or as otherwise defined herein.
The present application claims priority from a U.S. provisional patent application Ser. No. 63/597,347 filed Nov. 9, 2023, and the disclosure of which are incorporated by reference in their entirety.
Number | Date | Country | |
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63597347 | Nov 2023 | US |