Semitransparent organic photovoltaics (ST‐OPVs) have great potential for use in renewable energy technologies. In bulk‐heterojunction (BHJ) ST‐OPVs, a compromise is necessary between the visible ...light transmittance (VLT) and the power conversion efficiency (PCE). A sequential deposition (SD) strategy that involves individually depositing a polymer donor layer (D) and a small‐molecule acceptor layer (A) as the active layer is presented; where molecular diffusion occurring at the interfacial region results in a pseudo p–i–n structure. PBDB‐T‐2F(D)/Y6(A) ST‐OPVs are fabricated with different active layer thicknesses—at 115 nm, the SD (D:A/75:40 nm) and BHJ devices (D:A/1:1.2 w) provide the champion PCE of 12.91% (VLT of 14.5%) and 12.77% (VLT of 13.4%), respectively; at 85 nm, the SD (D:A/45:40 nm) and BHJ devices (D:A/1:1.2 w) provide a PCE of 12.22% (VLT of 22.2%) and 11.23% (VLT of 16.6%), respectively. This trend indicates SD devices have larger PCE and VLT values than the BHJ devices at a given active layer thickness, and the enhancements of PCE and VLT values by the SD structures against the BHJ structures become more pronounced as the active layer thickness reduced. The SD strategy provides a new approach for achieving ST‐OPVs with both high efficiency and high transparency.
In typical semitransparent organic photovoltaics (ST‐OPVs) that incorporate bulk heterojunction (BHJ) active layers, a compromise is made between the visible light transmittance (VLT) and power conversion efficiency (PCE). A new strategy with a sequential‐deposition (SD) active layer involving pseudo p–i–n structures provides ST‐OPVs with simultaneously higher PCE and VLT than that of the BHJ devices at the same layer thickness.
The phosphor‐converted light‐emitting diode (PC‐LED) has become an indispensable solid‐state lighting and display technologies in the modern society. Nevertheless, the use of scarce rare‐earth ...elements and the thermal quenching (TQ) behavior are still two most crucial issues yet to be solved. Here, this work successfully demonstrates a highly efficient and thermally stable green emissive MnI2(XanPO) crystals showing a notable photoluminescence quantum yield (PLQY) of 94% and a super TQ resistance from 4 to 623 K. This unprecedented superior thermal stability is attributed to the low electron–phonon coupling and the unique rigid crystal structure of MnI2(XanPO) over the whole temperature range based on the temperature‐dependent photoluminescence (PL) and single crystal X‐ray diffraction (SCXRD) analyses. Considering these appealing properties, green PC‐LEDs with a power efficacy of 102.5 lm W−1, an external quantum efficiency (EQE) of 22.7% and a peak luminance up to 7750 000 cd m−2 are fabricated by integrating MnI2(XanPO) with commercial blue LEDs. Moreover, the applicability of MnI2(XanPO) in both micro‐LEDs and organic light‐emitting diodes (OLEDs) is also demonstrated. In a nutshell, this study uncovers a candidate of highly luminescent and TQ resistant manganese halide suitable for a variety of emission applications.
A highly efficient and thermally stable manganese halide crystal, MnI2(XanPO) is demonstrated. The low electron–phono coupling along with rigid crystal structure contributes to excellent photoluminescent quantum yield of 94% with unprecedented near zero thermal quenching from 4 to 623 K. The crystals find their applications in light emitting diodes and micro light emitting diodes with excellent external quantum efficiency (EQE) up to 22.7% and power efficacy as high as 102.5 lm W−1.
Although vacuum‐deposited metal halide perovskite light‐emitting diodes (PeLEDs) have great promise for use in large‐area high‐color‐gamut displays, the efficiency of vacuum‐sublimed PeLEDs currently ...lags that of solution‐processed counterparts. In this study, highly efficient vacuum‐deposited PeLEDs are prepared through a process of optimizing the stoichiometric ratio of the sublimed precursors under high vacuum and incorporating ultrathin under‐ and upper‐layers for the perovskite emission layer (EML). In contrast to the situation in most vacuum‐deposited organic light‐emitting devices, the properties of these perovskite EMLs are highly influenced by the presence and nature of the upper‐ and presublimed materials, thereby allowing us to enhance the performance of the resulting devices. By eliminating Pb° formation and passivating defects in the perovskite EMLs, the PeLEDs achieve an outstanding external quantum efficiency (EQE) of 10.9% when applying a very smooth and flat geometry; it reaches an extraordinarily high value of 21.1% when integrating a light out‐coupling structure, breaking through the 10% EQE milestone of vacuum‐deposited PeLEDs.
By cleverly introducing vacuum‐sublimed ultrathin upper‐ and under‐layer adjacent to inorganic perovskite emission layer to inhibit Pb0 trap forming and enhance radiative recombination, all‐vacuum deposited perovskite light emission diodes are demonstrated with record‐high external quantum efficiencies up to 10.9% and 21.1% without and with a light out‐coupling structure, respectively.
In this work, three novel bipolar host materials TPA-SA, 3CBZ-SA and 4CBZ-SA have been designed and synthesized by incorporating triphenyl amine and carbazole as donor and benzothiadiazine ...1,1-dioxide as an acceptor. These molecules exhibit moderately high triplet energies and bipolar carrier transport characteristics (ambipolarity) which is useful for the exothermic energy transfer to the dopants and also for the balanced carrier injection/transport in the emissive layers. These materials exhibited good performances in PhOLEDs and furnished external quantum efficiency in the range of 10.0–15.0%. Notably, a red phosphorescent device using TPA-SA as the host doped with Ir(pq)2(acac) exhibited a maximum EQE, power efficiency and current efficiency of 15.0%, 16.0 lm/W, and 25.3 cd A−1, respectively.
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•Three novel bipolar host materials TPA-SA, 3 CBZ-SA and 4 CBZ-SA have been synthesized by incorporating triphenyl amine, carbazole as donor and Benzothiadiazine 1,1-dioxide as an acceptor.•Easy to synthesize and chromatography free purification•First report using Benzothiadiazine 1,1-dioxide as acceptor unit•All the three materials have excellent thermal as well as photophysical properties•A red phosphorescent device using TPA-SA as the host doped with Ir(pq)2(acac) exhibited a maximum EQE of 15%.
We explored the impact of gamma settings on visual experiences in diverse TV configurations, revealing user acceptability influenced by backlight brightness and color gamut. The findings challenge ...the traditional fixed gamma value, suggesting a need for tailored adjustments to align with diverse viewer preferences in different TV setups.
Visible light communication (VLC) has emerged as a cutting-edge high-speed communication technology, poised to meet the surging capacity demands of 6G networks. Micro-light-emitting diodes (μLEDs) ...are considered as the light sources for achieving high-speed VLC, distinguished by their remarkable modulation bandwidths. However, achieving broadband white light emission hinges on the utilization of color-conversion materials with wide emission spectra. The transmission speed of the white-light system is inherently constrained by the characteristics of these color-conversion materials. In this work, we demonstrate CC-MP7 and CC-MP8, two derivatives of phenothiazine/dimesitylborane, as color conversion materials in a semipolar (20–21) micro-LED-based white-light system for high-speed VLC. The color conversion layers possess wide emission spectra, enabling them to achieve excellent color rendering performance when combined with blue micro-LEDs. CC-MP7 and CC-MP8 demonstrate rapid photoluminescence decay characteristics, thereby enhancing the modulation bandwidth of the color-conversion layer in the white-light system. The resulting bandwidths achieved by CC-MP7 and CC-MP8 are 210 and 240 MHz, respectively, which represents an approximately 45-fold increase compared to ordinary phosphors. By combining semipolar (20–21) micro-LEDs with CC-MP7 and CC-MP8, the resulting white-light systems exhibit correlated color temperatures of 6860 and 7500 K, CIE coordinates of (0.3009, 0.3577) and (0.2958, 0.3129), and color-rendering indexes of 80 and 85, respectively. Furthermore, both systems offer high bandwidths of 1063 and 1084 MHz with the data rates of 1.72 Gbps and 1.74 Gbps using non-return-to-zero on–off keying (NRZ-OOK) format, respectively, indicating the significant potential of CC-MP7 and CC-MP8 for practical applications in VLC.
In this work, light extraction efficiency of organic light-emitting diodes (OLEDs) with a spin-coated polyimide/porous silica hybrids were enhanced. The polyimide/porous silica thin films (C1 and C2) ...were accomplished by spin coating a hybrid film composed of a polyimide-silica composite blended with various amount of porous silica nanoparticles into the opposite site of ITO glass. The optical, thermal, and morphology properties were controlled by adding various amount of porous silica. The incorporation of light extraction layer improved the maximum external quantum efficiency (EQE) by as much as 24.8% based on integrating sphere measurement condition when compared to that of a reference device without a light extraction layer. Furthermore, the device utilizing the light extraction layer showed identical EL spectra as the reference device did. Additionally, the optical emission distribution of the device was close to the Lambertian profile. The polyimide/porous silica hybrids demonstrated in this work are useful and efficient for OLED device for the enhancement of EL performance, indicating the potential in a wide range of applications, such as displays, lightings and so on.
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•The polyimide/porous silica light extraction films were accomplished by spin coating a hybrid film composed of a polyimide-silica composite blended with various amount of porous silica nanoparticles.•The incorporation of light extraction layer improved the maximum external quantum efficiency (EQE) by as much as 24.8%.•The device utilizing the light extraction layer showed identical EL spectra as the reference device did.
Organic light-emitting diodes (OLEDs) have shown great success in the display applications recently. However, the applications of OLEDs in lighting are still limited due to their complex device ...structures. Here, we developed a novel phosphor doped glass substrate with both high scattering and excellent color conversion capability to greatly simplify the device structures of white organic light-emitting diodes (WOLEDs). A simple-structured WOLED comprising a blue OLED and the scattering fluorescent substrate was demonstrated to realize high quality white light for lighting applications. The WOLED exhibits a turn-on voltage of 2.7 V, a maximum power efficiency of 29.8 lm/W, an external quantum efficiency (EQE) of 14.2%, a color rendering index (CRI) of 86, and a correlated color-temperature (CCT) of 3900 K. The low turn-on voltage can be attributed to the single emissive layer structure used in the WOLED. The high power efficiency as well as the high EQE are due to both the high color conversion efficiency and the high scattering capability of the fluorescent substrate. In addition, the WOLED is favorable for high-quality solid-state lighting in our daily life due to its high color rendering ability along with an adequate CCT CC.
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•A fluorescent substrate was proposed for simple structured WOLED with promising device efficiency and color rendering capability.•The function of the proposed fluorescent substrates was analyzed and discussed.•The WOLEDs utilizing the fluorescent substrates exhibited an EQE of 14.2% and CRI of 86.
In article number 2003576, Kung‐Hwa Wei and co‐workers demonstrate that semi‐transparent organic photovoltaics with a sequential deposited (SD) active layer—individually deposited polymer donor layer ...and a small‐molecule acceptor layer—forming pseudo p–i–n structures have larger power conversion efficiency and transmittance values than those for the devices with bulk heterojunction (BHJ) structures, and the enhancements for SD versus BHJ devices increase with the decreasing active layer thickness.
Although semitransparent organic photovoltaics (ST-OPVs) are attractive components of various building-integrated photovoltaic applications, there is an intrinsic trade-off in their power conversion ...efficiencies (PCEs) and average visible transmissions (AVTs)because the photocurrent generated usually requires substantial absorption in the visible light that determines transmission. In this paper, we describe a vertically stacked tunable multiheterojunction strategy toward highly efficient ST-OPVs that simultaneously maintain high AVTs. The vertical triheterojunctions of the active layer comprise one polymer donor, D18, and two small molecule acceptors, Y1 and Y6, that were formed with a sequentially deposited (SD) method. The triheterojunction structures not only introduced cascading energy levels of their lowest unoccupied molecular energy levels that aligned in parallel to the charge extraction direction but also can be tuned by varying their relative thicknesses, thereby significantly improving charge transport in the ST-OPVs without severely suffering AVT losses. We demonstrate the universality and broad tunability of this technique for balancing the PCEs and AVTs of the devices. Our ST-OPVs achieved champion PCEs as high as 13.9% at an AVT of 22.8% (100 nm active layer with deposited trilayers having D18, Y1, and Y6 at 45, 5, and 50 nm, respectively) and 13.5% at an AVT of 23.8% (100 nm active layer with deposited trilayers having D18, Y1, and Y6 at 40, 10, and 50 nm, respectively), while the PCE of the device with a bulk heterojunction (BHJ) D18/Y6 (1:1 wt) active layer at 100 nm is 12.3% at an AVT of 17.0%. Relative to the conventional BHJ devices, the PCEs of the both types of SD trilayer devices increased by at least 10%, while the AVTs increased by at least 25%, indicating the effectiveness of the vertical multiheterojunction structures. These efficiencies of the SD trilayer devices are among one of the best records for such ST-OPVs at comparable AVTs.
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