Search

The power conversion efficiencies (PCEs) of polycrystalline perovskite (PVK) solar cells (SCs) (PC-PeSCs) have rapidly increased. However, PC-PeSCs are intrinsically unstable without encapsulation, and their efficiency drops during large-scale production; these problems hinder the commercial viability of PeSCs. Stability can be increased by using colloidal PVK nanocrystals (c-PeNCs), which have high surface strains, low defect density, and exceptional crystal quality. The use of c-PeNCs separates the crystallization process from the film formation process, which is preponderant in large-scale fabrication. Consequently, the use of c-PeNCs has substantial potential to overcome challenges encountered when fabricating PC-PeSCs. Research on colloidal nanocrystal-based PVK SCs (NC-PeSCs) has increased their PCEs to a level greater than those of other quantum-dot SCs, but has not reached the PCEs of PC-PeSCs; this inferiority significantly impedes widespread application of NC-PeSCs. This review first introduces the distinctive properties of c-PeNCs, then the strategies that have been used to achieve high-efficiency NC-PeSCs. Then it discusses in detail the persisting challenges in this domain. Specifically, the major challenges and solutions for NC-PeSCs related to low short-circuit current density J sc are covered. Last, the article presents a perspective on future research directions and potential applications in the realm of NC-PeSCs., (© 2024 Wiley‐VCH GmbH.)

The small nanoparticle size and long-chain ligands in colloidal metal halide perovskite quantum dots (PeQDs) cause charge confinement, which impedes exciton dissociation and carrier extraction in PeQD solar cells, so they have low short-circuit current density J sc , which impedes further increases in their power conversion efficiency (PCE). Here, a re-assembling process (RP) is developed for perovskite nanocrystalline (PeNC) films made of colloidal perovskite nanocrystals to increase J sc in PeNC solar cells. The RP of PeNC films increases their crystallite size and eliminates long-chain ligands, and thereby overcomes the charge confinement in PeNC films. These changes facilitate exciton dissociation and increase carrier extraction in PeNC solar cells. By use of this method, the gradient-bandgap PeNC solar cells achieve a J sc = 19.30 mA cm -2 without compromising the photovoltage, and yield a high PCE of 16.46% with negligible hysteresis and good stability. This work provides a new strategy to process PeNC films and pave the way for high performance PeNC optoelectronic devices., (© 2023 Wiley-VCH GmbH.)

MXenes constitute a rapidly growing family of 2D materials that are promising for optoelectronic applications because of numerous attractive properties, including high electrical conductivity. However, the most widely used titanium carbide (Ti 3 C 2 T x ) MXene transparent conductive electrode exhibits insufficient environmental stability and work function (WF), which impede practical applications Ti 3 C 2 T x electrodes in solution-processed optoelectronics. Herein, Ti 3 C 2 T x MXene film with a compact structure and a perfluorosulfonic acid (PFSA) barrier layer is presented as a promising electrode for organic light-emitting diodes (OLEDs). The electrode shows excellent environmental stability, high WF of 5.84 eV, and low sheet resistance R S of 97.4 Ω sq -1 . The compact Ti 3 C 2 T x structure after thermal annealing resists intercalation of moisture and environmental contaminants. In addition, the PFSA surface modification passivates interflake defects and modulates the WF. Thus, changes in the WF and R S are negligible even after 22 days of exposure to ambient air. The Ti 3 C 2 T x MXene is applied for large-area, 10 × 10 passive matrix flexible OLEDs on substrates measuring 6 × 6 cm. This work provides a simple but efficient strategy to overcome both the limited environmental stability and low WF of MXene electrodes for solution-processable optoelectronics., (© 2022 Wiley-VCH GmbH.)

Conventional organic light-emitting devices without an encapsulation layer are susceptible to degradation when exposed to air, so realization of air-stable intrinsically-stretchable display is a great challenge because the protection of the devices against penetration of moisture and oxygen is even more difficult under stretching. An air-stable intrinsically-stretchable display that is composed of an intrinsically-stretchable electroluminescent device (SELD) integrated with a stretchable color-conversion layer (SCCL) that contains perovskite nanocrystals (PeNCs) is proposed. PeNCs normally decay when exposed to air, but they become resistant to this decay when dispersed in a stretchable elastomer matrix; this change is a result of a compatibility between capping ligands and the elastomer matrix. Counterintuitively, the moisture can efficiently passivate surface defects of PeNCs, to yield significant increases in both photoluminescence intensity and lifetime. A display that can be stretched up to 180% is demonstrated; it is composed of an air-stable SCCL that down-converts the SELD's blue emission and reemits it as green. The work elucidates the basis of moisture-assisted surface passivation of PeNCs and provides a promising strategy to improve the quantum efficiency of PeNCs with the aid of moisture, which allows PeNCs to be applied for air-stable stretchable displays., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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 × 10(6) A W(-1) ), and fast photoswitching speed (rising/decaying time: 58/263 ms)., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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 × 10(6) A W(-1) ), fast photoswitching speed (rising/decaying time: 58/263 ms), and broad photodetection range (possible above 1064 nm)., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The effects of triphenylphosphine (PPh3 )-based n-doping and hexagonal boron nitride (h-BN) insertion on a tungsten diselenide (WSe2 ) photodetector are systematically studied, and a very high performance WSe2 /h-BN heterostucture-based photodetector is demonstrated with a record photoresponsivity (1.27 × 10(6) A W(-1) ) and temporal photoresponse (rise time: 2.8 ms, decay time: 20.8 ms) under 520 nm wavelength and 5 pW power laser illumination., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)