Monolithic perovskite/organic tandem solar cells (POTSCs) have significant advantages in next‐generation flexible photovoltaics, owing to their capability to overcome the Shockley–Queisser limit and ...facile device integration. However, the compromised sub‐cells performance challenges the fabrication of high‐efficiency POTSCs. Especially for all‐inorganic wide‐bandgap perovskite front sub‐cells (AIWPSCs) based n‐i‐p structured POTSCs (AIPOTSCs), for which the power conversion efficiency (PCE) is much lower than organic–inorganic mixed‐halide wide‐bandgap perovskite based POTSCs. Herein, an ionic liquid, methylammonium formate (MAFm), based dual‐interface engineering approach is developed to modify the bottom and top interfaces of wide‐bandgap CsPbI2Br films. In particular, the Fm− group of MAFm can effectively passivate the interface defects, and the top interface modification can facilitate the formation of uniform perovskite films with enlarged grain size, thereby mitigating the defects and perovskite grain boundaries induced carrier recombination. As a result, CsPbI2Br‐based AIWPSCs with a high PCE of 17.0% and open‐circuit voltage (VOC) of 1.347 V are achieved. By integrating these dual‐interface engineered CsPbI2Br‐based front sub‐cells with the narrow‐bandgap PM6:CH1007‐based rear sub‐cells, a record PCE of 23.21% is obtained for AIPOTSCs, illustrating the potential of AIPOTSCs for achieving high‐efficiency tandem solar cells.
The ionic liquid, methylammonium formate (MAFm), based dual‐interface engineering is developed to modify the bottom and top interfaces of wide‐bandgap CsPbI2Br films, which enables a high PCE of 17.0% and VOC of 1.347 V for CsPbI2Br‐based wide‐bandgap sub‐cells. High‐efficiency monolithic perovskite/organic tandem solar cells based on these sub‐cells demonstrate a champion PCE of 23.21% and VOC of 2.10 V.
Perovskite light‐emitting diodes (PeLEDs) have shown great potential for low‐cost display and lighting technologies, and all‐inorganic blue PeLEDs are recognized as a promising substitute for blue ...fluorescent/phosphorescent organic light‐emitting diodes (OLEDs) owing to their superior color purity and great stability potential. However, confined by the solution fabrication process, depositing multi‐layered white PeLEDs remains a challenge. Here, a newly designed hybrid perovskite/organic tandem white LED (POTWLED), integrated with a bottom blue PeLED unit and a top orange/(orange + red) OLED unit, to prevent damage to the underlying perovskite layer caused by the deposition of the top emitting layers, is reported. To optimize the performance of POTWLEDs, a conductive passivator of 2,8‐bis(diphenylphosphoryl)dibenzob,d thiophene, with a strong surface binding group of P═O, is introduced to passivate perovskite defects, which promotes a maximum external quantum efficiency (EQE) of 17.3% for blue PeLEDs with an emission peak at 488 nm. As a result, based on the optimized blue PeLED units, a maximum EQE of 23.9% with a low color temperature of 2522 K is obtained for POTWLEDs, which is the highest efficiency for perovskite‐based WLEDs, illustrating the great potential of the hybrid tandem device in fabricating high‐performance perovskite‐based WLEDs.
Novel structured hybrid perovskite/organic tandem white LED (POTWLED) by integrating a 2,8‐bis(diphenylphosphoryl)dibenzob,d thiophene passivated bottom blue perovskite light‐emitting diode unit and a top organic/(orange + red) organic light‐emitting diode unit is developed, which promotes the fabrication of high‐performance three‐color POTWLEDs with a maximum external quantum efficiency of 23.9% with a corresponding color temperature of 2522 K.
Functional passivators are conventionally utilized in modifying the crystallization properties of perovskites to minimize the non‐radiative recombination losses in perovskite light‐emitting diodes ...(PeLEDs). However, the weak anchor ability of some commonly adopted molecules has limited passivation ability to perovskites and even may desorb from the passivated defects in a short period of time, which bring about plenty of challenges for further development of high‐performance PeLEDs. Here, a multidentate molecule, formamidine sulfinic acid (FSA), is introduced as a novel passivator to perovskites. FSA has multifunctional groups (S≐O, C≐N and NH2) where the S≐O and C≐N groups enable coordination with the lead ions and the NH2 interacts with the bromide ions, thus providing the most effective chemical passivation for defects and in turn the formation of highly stable perovskite emitters. Moreover, the interaction between the FSA and octahedral PbBr64− can inhibit the formation of unfavorable low‐n domains to further minimize the inefficient energy transfer inside the perovskite emitters. Therefore, the FSA passivated green‐emitting PeLED exhibits a high external quantum efficiency (EQE) of 26.5% with fourfold enhancement in operating lifetime as compared to the control device, consolidating that the multidentate molecule is a promising strategy to effectively and sustainably passivate the perovskites.
A multidentate molecule (Formamidine Sulfinic Acid, FSA) to passivate the perovskite for efficient light‐emitting devices. Owing to its multiple roles of guaranteeing sufficient passivation durability and minimizing the energy loss, green PeLEDs based on the FSA‐perovskite films shows a superior EQE of 26.5%.
Thanks to the extensive efforts toward optimizing perovskite crystallization properties, high‐quality perovskite films with near‐unity photoluminescence quantum yield are successfully achieved. ...However, the light outcoupling efficiency of perovskite light‐emitting diodes (PeLEDs) is impeded by insufficient light extraction, which poses a challenge to the further advancement of PeLEDs. Here, an anisotropic multifunctional electron transporting material, 9,10‐bis(4‐(2‐phenyl‐1H‐benzodimidazole‐1‐yl)phenyl) anthracene (BPBiPA), with a low extraordinary refractive index (ne) and high electron mobility is developed for fabricating high‐efficiency PeLEDs. The anisotropic molecular orientations of BPBiPA can result in a low ne of 1.59 along the z‐axis direction. Optical simulations show that the low ne of BPBiPA can effectively mitigate the surface plasmon polariton loss and enhance the photon extraction efficiency in waveguide mode, thereby improving the light outcoupling efficiency of PeLEDs. In addition, the high electron mobility of BPBiPA can facilitate balanced carrier injection in PeLEDs. As a result, high‐efficiency green PeLEDs with a record external quantum efficiency of 32.1% and a current efficiency of 111.7 cd A−1 are obtained, which provides new inspirations for the design of electron transporting materials for high‐performance PeLEDs.
An anisotropic anthracene derivative, 9,10‐bis(4‐(2‐phenyl‐1H‐benzodimidazole‐1‐yl)phenyl) anthracene, featuring a low extraordinary refractive index and high electron mobility, is developed as an efficient electron transporting material for perovskite LEDs (PeLEDs) to enhance light outcoupling efficiency and carrier balance of the devices, which promotes green PeLEDs with a record EQE of 32.1%.
Metal halide-based perovskites are regarded as promising candidates for light-emitting diodes (LEDs) owing to their high color purity, tunable bandgap and solution processability. However, poor ...active-layer morphology and non-radiative charge recombination are still the main obstacles for practical use in displays and lighting. Here, we report a facile method to achieve high-performance green emitting perovskite light-emitting diodes (PeLEDs) by inserting an interface buffer layer (BL) based on an amphipathic conjugated molecule, betaine. We show evidence that the betaine layer controls the grain size of the perovskite and hence increases the crystalline nucleation sites, which ultimately leads to a high photoluminescence quantum yield (PLQY) and a device with an external quantum efficiency (EQE) of 11.1%. In addition, the current leakage is significantly reduced due to the high quality crystallization of the thin film. These results indicate that the interface BL is an effective strategy to boost the efficiency of PeLEDs.
In addition to mobile and TV displays, there is a trend of organic LEDs being applied in niche markets, such as microdisplays, automobile taillights, and photobiomodulation therapy. These ...applications mostly do not require to be flexible in form but need to have long operation lifetimes and storage lifespans. Using traditional glass encapsulation may not be able to fulfill the rigorous product specification, and a hybrid encapsulation method by combining glass and thin-film encapsulation will be the solution. Conventional thin-film encapsulation technology generally involves organic and inorganic multilayer films that are thick and have considerable stress. As a result, when subjected to extreme heat and stress, the film easily peels off. Herein, the water vapor transmission rate (WVTR) of a 2 µm silicon nitride film prepared at 85 °C is less than 5 × 10
g/m
/day and its stress is optimized to be 23 MPa. Red organic LEDs are passivated with the hybrid encapsulation, and the
lifetime reaches nearly 10 years if the LED is continuously driven at an initial luminance of 1000 cd/m
. In addition, a storage lifespan of over 17 years is achieved.
Energy matching between the triplet level of the exciplex hosts and phosphorescent emitters is of particular importance to achieve highly efficient exciplex-based white organic light emitting diodes ...(WOLEDs). Herein, we design a novel exciplex host and use it for WOLEDs by arranging rational multiple-exciplex hosts in emissive layers. The resulting two-color warm WOLED, by doping blue and orange phosphorescent emitters, shows a maximum forward-viewing power efficiency and external quantum efficiency (EQE) of 104.6 lm W
−1
and 30.9%, respectively. Significantly, the EQE still remains 22.1% at 5000 cd m
−2
. Meanwhile, the three-color warm WOLED has a high color rendering index of over 80 with a maximum EQE of 27.0% and the EQE can remain 21.3% at 5000 cd m
−2
. These results indicate that rational arrangement of multiple-exciplex hosts in emissive layers is promising for the fabrication of highly efficient WOLEDs.
Designing a novel exciplex host and arranging rational multiple-exciplex hosts in emissive layers.Two and three color WOLEDs based on multiple exciplex hosts exhibited maximum EQEs of 30.9% and 27.0%, respectively. Remarkedly, their EQEs remained at 22.1% and 21.3% at a high luminance of 5000 cd m
−2
.
Luminous efficiency, color purity and spectral stability of white organic light-emitting diodes (WOLEDs) remain the key challenges for display applications based on the "white plus color filter" ...approach. To tackle these issues, we developed high-efficiency and color-stable WOLEDs in natural color based on all thermally activated delayed fluorescence (TADF) emitters constructed with a blue-orange-blue sandwich emissive layer (EML) structure. The balanced carrier transport and good exciton confinement in this system facilitate excitons broadly forming over the recombination zone and thus realizing a balance of blue and orange emissions in the EMLs successfully. As a result, the device exhibits high-performance pure white emission with the ideal and stable Commission International de I'Eclairage (CIE) coordinates (
x
,
y
) of (0.33 ± 0.01, 0.33 ± 0.01) and a high color rendering index (CRI) of 81-83 at a luminance in the range of 250 to 5000 cd m
−2
. The device shows a maximum external quantum efficiency (EQE) and current efficiency (CE) of 12.0% and 28.0 cd A
−1
, respectively. The full-TADF WOLEDs with a sandwich EML not only show ideal CIE coordinates and CRIs, but also exhibit excellent color stability. We anticipate that our findings can provide an efficient strategy to realize color stable and high color-purity WOLEDs through the full TADF mechanism and have great potential for display applications.
WOLEDs with stable natural white emission based on all-TADF emitters.
All-inorganic halide perovskites with superior optoelectronic properties are promising materials for efficient perovskite light-emitting diodes. However, they usually suffer from a large grain size ...(hundreds of nanometers), high surface roughness and poor stability during the spin coating process. Here, we report a facile strategy to fabricate a uniform and flat CsPbBr
3
film. A small amount of lecithin (LE) introduced into CsPbBr
3
precursor solution can promote the formation of small CsPbBr
3
grains that remarkably improve the uniformity of perovskite films with a surface roughness of about 2.2 nm. Furthermore, the CsPbBr
3
–LE films display excellent fluorescence stability in ambient air and LED devices based on the CsPbBr
3
–5 wt% LE film exhibit a current efficiency (CE) of 24 cd A
−1
with an external quantum efficiency (EQE) of 6.5%. Therefore, it is anticipated that the findings of the present study will have great potential to boost the development of PeLEDs.
Hybrid white organic light-emitting diodes (WOLEDs) have drawn great attention both for display and solid-state lighting purposes because of the combined advantages of desirable stability of ...fluorescent dyes and high efficiency of phosphorescent materials. However, in most WOLEDs, obtaining high efficiency often requires complex device structures. Herein, we achieved high-efficiency hybrid WOLEDs using a simple but efficacious structure, which included a non-doped blue emissive layer (EML) to separate the exciton recombination zone from the light emission region. After optimization of the device structure, the WOLEDs showed a maximum power efficiency (PE), current efficiency (CE), and external quantum efficiency (EQE) of 82.3 lm/W, 70.0 cd/A, and 22.2%, respectively. Our results presented here provided a new option for promoting simple-structure hybrid WOLEDs with superior performance.
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