The effects of triphenylphosphine and (3‐aminopropyl)triethoxysilane on a rhenium diselenide (ReSe2) photodetector are systematically studied by comparing with conventional MoS2 devices. This study ...demonstrates a very high performance ReSe2 photodetector with high photoresponsivity (1.18 × 106 A W−1), fast photoswitching speed (rising/decaying time: 58/263 ms), and broad photodetection range (possible above 1064 nm).
The effects of graphene n‐doping on a metal–graphene contact are studied in combination with 1D edge contacts, presenting a record contact resistance of 23 Ω μm at room temperature (19 Ω μm at 100 ...K). This contact scheme is applied to a graphene–perovskite hybrid photodetector, significantly improving its performance (0.6 → 1.8 A W−1 in photoresponsivity and 3.3 × 104 → 5.4 × 104 Jones in detectivity).
Since the rediscovery of graphene in 2004, this material has attracted an enormous amount of interest owing to its unique structural, mechanical, electronic, and optical properties. Beyond this, the ...unique properties of graphene have also triggered extensive research on other two‐dimensional (2D) materials including transition metal dichalcogenides (TMDs), particularly for electronic and optoelectronic device applications. In particular, not only single junction but also various heterojunction devices based on 2D materials have afforded novel functionality and advances in many research fields. The availability of various 2D materials could allow the formation of a wide variety of heterojunctions with desired band alignments, thereby providing a powerful fabrication process platform for high‐performance electronic and optoelectronic devices. In this review, the important fabrication techniques of i) doping, ii) contact engineering, and iii) heterojunction formation for improving the performance of 2D‐material‐based devices are first introduced. Promising 2D‐material‐based electronic and optoelectronic devices are then discussed, including lateral/vertical field‐effect transistors (FETs), negative differential resistance (NDR) devices, memory, photodetectors, photovoltaics, and light‐emitting diode (LED) devices.
Important fabrication techniques of doping, contact engineering, and heterojunction formation are introduced for improving the performance of 2D‐material‐based devices. In addition, promising 2D‐material‐based electronic and optoelectronic devices are discussed: lateral/vertical FETs, NDR devices, memory, photodetectors, photovoltaics, and LED devices.
The unique properties of organic photovoltaics (OPVs) offer great promise in emerging applications such as wearable electronics or the Internet of Things. For their successful utilization, OPV ...operation should be designed for versatile irradiation circumstances in addition to solar light since they should be capable of providing electric power when there is no sunlight or when they operate indoors. Here, a quaternary OPV (Q‐OPV) as a semitransparent, colorful energy platform that operates efficiently under both solar and artificial light irradiation is demonstrated. The experimentally optimized Q‐OPV shows a broadened spectral response and improved charge transport process with suppressed recombination, thereby providing high output powers that are sufficient to autonomously operate low‐power electronic devices. In addition, the Q‐OPV benefits from improved morphological stability with a reduced driving force for grain growth by the increased entropy in the quaternary blend system. The important features of the Q‐OPV platform such as semitransparency, high tolerance to film thickness, and color codability, while pursuing the improved performance and thermal durability, further open new opportunities as an all‐day (24/7/365) power generator in broad practical applications.
Quaternary blend organic photovoltaics (Q‐OPVs) exhibit efficient operation under diverse irradiation conditions and improved thermal durability with suppressed morphological evolution during operation. The unique properties of the Q‐OPVs such as semitransparency, high film thickness tolerance, and color codability expand their applicability to emerging energy systems, which operate autonomously by any incident light all day, even when there is no sunlight.
Optimizing the interfacial contacts between the photoactive layer and the electrodes is an important factor in determining the performance of organic solar cells (OSCs). A charge‐selective layer with ...tailored electrical properties enhances the charge collection efficiency and interfacial stability. Here, the potential of hydrogenated TiO2 nanoparticles (H‐TiO2 NPs) as an efficient electron‐selective layer (ESL) material in OSCs is reported for the first time. The H‐TiO2 is synthesized by discharge plasma in liquid at atmospheric pressure, which has the benefits of a simple one‐pot synthesis process, rapid and mild reaction conditions, and the capacity for mass production. The H‐TiO2 exhibits high conductivity and favorable energy level formation for efficient electron extraction, providing a basis for an efficient bilayer ESL system composed of conjugated polyelectrolyte/H‐TiO2. Thus, the enhanced charge transport and extraction efficiency with reduced recombination losses at the cathode interfacial contacts is achieved. Moreover, the OSCs composed of H‐TiO2 are almost free of light soaking, which has been reported to severely limit the performance and stability of OSCs based on conventional TiO2 ESLs. Therefore, H‐TiO2 as a new efficient, stable, and cost‐effective ESL material has the potential to open new opportunities for optoelectronic devices.
This study demonstrates the potential of hydrogenated TiO2 (H‐TiO2) as an efficient electron‐selective layer in optoelectronic devices. The H‐TiO2 is simply one‐pot mass‐produced using a discharge plasma system in liquid at atmospheric pressure. The H‐TiO2 exhibits high conductivity and favorable energy level formation, resulting in the high‐efficiency and light‐soaking‐free organic solar cells.
Abstract
Optimizing the interfacial contacts between the photoactive layer and the electrodes is an important factor in determining the performance of organic solar cells (OSCs). A charge‐selective ...layer with tailored electrical properties enhances the charge collection efficiency and interfacial stability. Here, the potential of hydrogenated TiO
2
nanoparticles (H‐TiO
2
NPs) as an efficient electron‐selective layer (ESL) material in OSCs is reported for the first time. The H‐TiO
2
is synthesized by discharge plasma in liquid at atmospheric pressure, which has the benefits of a simple one‐pot synthesis process, rapid and mild reaction conditions, and the capacity for mass production. The H‐TiO
2
exhibits high conductivity and favorable energy level formation for efficient electron extraction, providing a basis for an efficient bilayer ESL system composed of conjugated polyelectrolyte/H‐TiO
2
. Thus, the enhanced charge transport and extraction efficiency with reduced recombination losses at the cathode interfacial contacts is achieved. Moreover, the OSCs composed of H‐TiO
2
are almost free of light soaking, which has been reported to severely limit the performance and stability of OSCs based on conventional TiO
2
ESLs. Therefore, H‐TiO
2
as a new efficient, stable, and cost‐effective ESL material has the potential to open new opportunities for optoelectronic devices.
The effects of triphenylphosphine (PPh3) and (3‐amino‐propyl)triethoxysilane (APTES) on a rhenium diselenide (ReSe2) photodetector are systematically studied by J.‐H. Park and co‐workers on page 6711 ...in comparison with a conventional MoS2 device. A very high performance ReSe2 photodetector is demonstrated, which has a broad photodetection range, high photoresponsivity (1.18 × 106 A W−1), and fast photoswitching speed (rising/decaying time: 58/263 ms).
The effects of graphene n‐doping on metal–graphene (M–G) contacts in combination with 1D edge contacts is discussed by J.‐H. Park and co‐workers, as described on page 864, presenting a record contact ...resistance of 23 Ω μm at room temperature (19 Ω μm at 100 K). This is lower than the value required for the latest Si CMOS technology. This contact scheme is applied to graphene–perovskite hybrid photo‐detectors, significantly improvement of its performance (0.6 → 1.8 A W−1 in photoresponsivity and 3.3 × 104 → 5.4 × 104 Jones in detectivity).
Here, we theoretically and experimentally investigate the impact of a high-Formula Omitted layer inserted between graphene and p-Si in a graphene/Si junction. We have achieved 86-fold and 222-fold ...reductions in a specific contact resistivity (Formula Omitted) by inserting 1-nm-thick Al2O3 and 2-nm-thick TiO2 in the graphene-semiconductor junction, respectively, corresponding to lowering the effective barrier height by 0.24 and 0.12 eV. Furthermore, we propose a graphene-induced gap state model that simultaneously considers the graphene's modulation by a gate bias and the effect of the high-Formula Omitted insertion.
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