The best performing modern optoelectronic devices rely on single‐crystalline thin‐film (SC‐TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low‐cost ...solution‐based methods, have achieved substantial success in various optoelectronic devices including solar cells, lasers, light‐emitting diodes, and photodetectors. However, to date, the performance of these perovskite devices based on polycrystalline thin‐film active layers lags behind the epitaxially grown semiconductor devices. Here, a photodetector based on SC‐TF perovskite active layer is reported with a record performance of a 50 million gain, 70 GHz gain‐bandwidth product, and a 100‐photon level detection limit at 180 Hz modulation bandwidth, which as far as we know are the highest values among all the reported perovskite photodetectors. The superior performance of the device originates from replacing polycrystalline thin film by a thickness‐optimized SC‐TF with much higher mobility and longer recombination time. The results indicate that high‐performance perovskite devices based on SC‐TF may become competitive in modern optoelectronics.
Improvement of optoelectronic device performance by using a single‐crystalline perovskite thin film is demonstrated by a photodetector. The simultaneously optimized perovskites thickness and crystallinity lead to a record detector performance of a 70 GHz gain‐bandwidth product and a 200‐photon detection limit.
We investigate thin film sensing capabilities of a terahertz (THz) metamaterial, which comprises of an array of single split gap ring resonators (SRRs). The top surface of the proposed metamaterial ...is covered with a thin layer of analyte in order to examine various sensing parameters. The sensitivity and corresponding figure of merit (FoM) of the odd and even resonant modes are analyzed with respect to different thicknesses of the coated analyte film. The sensing parameters of different resonance modes are elaborated and explained with appropriate physical explanations. We have also employed a semi-analytical transmission line model in order to validate our numerically simulated observations. Such study should be very useful for the development of metamaterials based sensing devices, bio-sensors etc in near future.
In this article, the excellent properties of state-of-the-art Cd-free Cu(In,Ga)(Se,S) 2 (CIGSSe) solar cells with Zn(O,S,OH) x /Zn 0.8 Mg 0.2 O double buffer layers, deposited by a combination of ...chemical bath deposition and atomic layer deposition techniques, are presented. By the replacement of conventional CdS buffer layers with this double buffer layer, the open-circuit voltage ( V oc ) deficit of the devices could be significantly reduced, and V oc increased by approximately 15 mV. In addition, the fill factor and short-circuit current were also improved, increasing the device efficiency by approximately 0.5 absolute percent compared with devices with CdS buffers. The Cd-free double buffer layer improved the device efficiency regardless of the bandgap of the CIGSSe absorber. The minority carrier lifetime ( τ ) measured via time-resolved photoluminescence became longer, indicating that carrier recombination is mitigated using the double buffer layer. Based on the device parameters extracted by fitting the Suns- V oc characteristics to the double-diode model, the longer τ could be attributed to the decreased recombination rate in the space-charge region, rather than in the bulk and at the interface. The best performing cell was evaluated by a reliable third party, the National Institute of Advanced Industrial Science and Technology; this cell achieved a new world record efficiency of 23.35% for 1-cm 2 -sized thin-film polycrystalline solar cells. The device parameters of this cell are also discussed in this article.
Monolithical integration of the promising optoelectronic material with mature and inexpensive silicon circuitry contributes to simplifying device geometry, enhancing performance, and expanding new ...functionalities. Herein, a lead‐free halide perovskite Cs3Bi2I9 single‐crystalline thin film (SCTF), with thickness ranging from 900 nm to 4.1 µm and aspect ratio up to 1666, is directly integrated on various substrates including Si wafer, through a facile and low‐temperature solution‐processing method. The growth kinetics of the lead‐free halide perovskite SCTF are elucidated by in situ observation, and the solution supersaturation is controlled to reduce the inverse‐temperature crystallization nucleation density and elongate the evaporation growth. The excellent lattice match and band alignment between Si(111) and Cs3Bi2I9(001) facets promote photogenerated charge dissociation and extraction, resulting in boosting the photoelectric sensitivity by 10–200 times compared with photodetectors based on other substrates. More importantly, this silicon‐compatible perovskite SCTF photodetector exhibits a high switching ratio of 3000 and a fast response of 1.5 µs, which are higher than most reported state‐of‐the‐art lead‐free halide perovskite photodetectors. This work not only gives an in‐depth understanding of the perovskite precursor solution chemistry, but also demonstrates the great potential of monolithical integration of lead‐free halide perovskite SCTF with a silicon wafer for high‐performance photodetectors.
A lead‐free halide perovskite Cs3Bi2I9 single‐crystalline thin film, with adjustable thickness and millimeter size, is directly integrated on various substrates including Si wafer, through a supersaturation‐controlled method. Benefiting from the incommensurate lattice match and suitable thinness, this silicon‐compatible perovskite photodetector is superior to most reported state‐of‐the‐art lead‐free halide perovskite photodetectors.
All-solid-state batteries (SSBs) are one of the most fascinating next-generation energy storage systems that can provide improved energy density and safety for a wide range of applications from ...portable electronics to electric vehicles. The development of SSBs was accelerated by the discovery of new materials and the design of nanostructures. In particular, advances in the growth of thin-film battery materials facilitated the development of all solid-state thin-film batteries (SSTFBs)—expanding their applications to microelectronics such as flexible devices and implantable medical devices. However, critical challenges still remain, such as low ionic conductivity of solid electrolytes, interfacial instability and difficulty in controlling thin-film growth. In this review, we discuss the evolution of electrode and electrolyte materials for lithium-based batteries and their adoption in SSBs and SSTFBs. We highlight novel design strategies of bulk and thin-film materials to solve the issues in lithium-based batteries. We also focus on the important advances in thin-film electrodes, electrolytes and interfacial layers with the aim of providing insight into the future design of batteries. Furthermore, various thin-film fabrication techniques are also covered in this review.
Despite the fact that antimony triselenide (Sb2Se3) thin‐film solar cells have undergone rapid development in recent years, the large open‐circuit voltage (VOC) deficit still remains as the biggest ...bottleneck, as even the world‐record device suffers from a large VOC deficit of 0.59 V. Here, an effective interface engineering approach is reported where the Sb2Se3/CdS heterojunction (HTJ) is subjected to a post‐annealing treatment using a rapid thermal process. It is found that nonradiative recombination near the Sb2Se3/CdS HTJ, including interface recombination and space charge region recombination, is greatly suppressed after the HTJ annealing treatment. Ultimately, a substrate Sb2Se3/CdS thin‐film solar cell with a competitive power conversion efficiency of 8.64% and a record VOC of 0.52 V is successfully fabricated. The device exhibits a much mitigated VOC deficit of 0.49 V, which is lower than that of any other reported efficient antimony chalcogenide solar cell.
A heterojunction post‐annealing treatment is utilized to suppress the nonradiative recombination for a highly competitive power conversion efficiency of 8.64% and a record open‐circuit voltage (VOC) of 520 mV in Sb2Se3 thin‐film solar cells. The VOC deficit of the device is lower than that of any other reported efficient antimony chalcogenide solar cells.
Multiple exciton generation (MEG) refers to the creation of two or more electron-hole pairs from the absorption of one photon. Although MEG holds great promise, it has proven challenging to ...implement, and questions remain about the underlying photo-physical dynamics in nanocrystalline as well as molecular media. Using the model system of pentacene/fullerene bilayers and femtosecond nonlinear spectroscopies, we directly observed the multiexciton (ME) state ensuing from singlet fission (a molecular manifestation of MEG) in pentacene. The data suggest that the state exists in coherent superposition with the singlet populated by optical excitation. We also found that multiple electron transfer from the ME state to the fullerene occurs on a subpicosecond time scale, which is one order of magnitude faster than that from the triplet exciton state.
Recently we have reported the room temperature fabrication of transparent and flexible thin film transistors on a polyethylene terephthalate (PET) film substrate using an ionic amorphous oxide ...semiconductor (IAOS) in an In2O3–ZnO–Ga2O3 system. These transistors exhibit a field effect mobility of ∼10cm2 (Vs)−1, which is higher by an order of magnitude than those of hydrogenated amorphous Si and pentacene transistors. This article describes a chemical design concept of IAOS, and its unique electron transport properties, and electronic structure, by comparing them with those of conventional amorphous semiconductors. High potential of IAOS for flexible electronics is addressed.
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