| 1. |
- Bao, Chunxiong, et al.
(author)
-
Bidirectional optical signal transmission between two identical devices using perovskite diodes
- 2020
-
In: NATURE ELECTRONICS. - : NATURE PUBLISHING GROUP. - 2520-1131. ; 3:3, s. 156-164
-
Journal article (peer-reviewed)abstract
- A solution-processed perovskite diode that functions as both optical transmitter and receiver can be used to build a monolithic pulse sensor and a bidirectional optical communication system. The integration of optical signal generation and reception into one device-thus allowing a bidirectional optical signal transmission between two identical devices-is of value in the development of miniaturized and integrated optoelectronic devices. However, conventional solution-processable semiconductors have intrinsic material and design limitations that prevent them from being used to create such devices with a high performance. Here we report an efficient solution-processed perovskite diode that is capable of working in both emission and detection modes. The device can be switched between modes by changing the bias direction, and it exhibits light emission with an external quantum efficiency of over 21% and a light detection limit on a subpicowatt scale. The operation speed for both functions can reach tens of megahertz. Benefiting from the small Stokes shift of perovskites, our diodes exhibit a high specific detectivity (more than 2 x 10(12) Jones) at its peak emission (~804 nm), which allows an optical signal exchange between two identical diodes. To illustrate the potential of the dual-functional diode, we show that it can be used to create a monolithic pulse sensor and a bidirectional optical communication system.
|
|
| 2. |
- Karlsson, Max, et al.
(author)
-
Mixed halide perovskites for spectrally stable and high-efficiency blue light-emitting diodes
- 2021
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
-
Journal article (peer-reviewed)abstract
- Bright and efficient blue emission is key to further development of metal halide perovskite light-emitting diodes. Although modifying bromide/chloride composition is straightforward to achieve blue emission, practical implementation of this strategy has been challenging due to poor colour stability and severe photoluminescence quenching. Both detrimental effects become increasingly prominent in perovskites with the high chloride content needed to produce blue emission. Here, we solve these critical challenges in mixed halide perovskites and demonstrate spectrally stable blue perovskite light-emitting diodes over a wide range of emission wavelengths from 490 to 451 nanometres. The emission colour is directly tuned by modifying the halide composition. Particularly, our blue and deep-blue light-emitting diodes based on three-dimensional perovskites show high EQE values of 11.0% and 5.5% with emission peaks at 477 and 467 nm, respectively. These achievements are enabled by a vapour-assisted crystallization technique, which largely mitigates local compositional heterogeneity and ion migration.
|
|
| 3. |
- Teng, Pengpeng, et al.
(author)
-
Degradation and self-repairing in perovskite light-emitting diodes
- 2021
-
In: Matter. - : Elsevier. - 2590-2393 .- 2590-2385. ; 4:11, s. 3710-3724
-
Journal article (peer-reviewed)abstract
- One of the most critical challenges in perovskite light-emitting diodes (PeLEDs) lies in poor operational stability. Although field dependent ion migration is believed to play an important role in the operation of perovskite optoelectronic devices, a complete understanding of how it affects the stability of PeLEDs is still missing. Here, we report a unique self-repairing behavior that the electroluminescence of moderately degraded PeLEDs can almost completely restore to their initial performance after resting. We find that the accumulated halides within the hole transport layer undergo back diffusion toward the surface of the perovskite layer during resting, repairing the vacancies and thus resulting in electroluminescence recovery. These findings indicate that one of the dominant degradation pathways in PeLEDs is the generation of halide vacancies at perovskite/hole transport layer interface during operation. We thus further passivate this key interface, which results in a high external quantum efficiency of 22.8% and obviously improved operational stability.
|
|
| 4. |
- Zhao, Haifeng, et al.
(author)
-
High-Brightness Perovskite Light-Emitting Diodes Based on FAPbBr(3) Nanocrystals with Rationally Designed Aromatic Ligands
- 2021
-
In: ACS Energy Letters. - : AMER CHEMICAL SOC. - 2380-8195. ; 6:7, s. 2395-2403
-
Journal article (peer-reviewed)abstract
- Despite rapid developments of light-emitting diodes (LEDs) based on emerging perovskite nanocrystals (PeNCs), it remains challenging to achieve devices with integrated high efficiencies and high brightness because of the insulating long-chain ligands used for the PeNCs. Herein, we develop highly luminescent and stable formamidinium lead bromide PeNCs capped with rationally designed short aromatic ligands of 2-naphthalenesulfonic acid (NSA) for LEDs. Compared with commonly used oleic acid ligands, the NSA molecules not only preserve the surface properties of the PeNCs during the purification but also notably improve the electrical properties of the assembled emissive layers, ensuring efficient charge injection/transport in the devices. The resulting champion LED with electroluminescence approaching the Rec. 2020 green primary color demonstrates a high brightness of 67 115 cd cm(-2) and a peak external quantum efficiency of 19.2%. More impressively, the device shows negligibly decreased efficiency at an elevated brightness of 20 000 cd cm(-2) and a well-retained efficiency of over 10% at around 65 000 cd cm(-2), presenting a breakthrough in LEDs based on PeNCs.
|
|
| 5. |
- Zou, Yatao, et al.
(author)
-
Manipulating crystallization dynamics through chelating molecules for bright perovskite emitters
- 2021
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
-
Journal article (peer-reviewed)abstract
- Molecular additives are widely utilized to minimize non-radiative recombination in metal halide perovskite emitters due to their passivation effects from chemical bonds with ionic defects. However, a general and puzzling observation that can hardly be rationalized by passivation alone is that most of the molecular additives enabling high-efficiency perovskite light-emitting diodes (PeLEDs) are chelating (multidentate) molecules, while their respective monodentate counterparts receive limited attention. Here, we reveal the largely ignored yet critical role of the chelate effect on governing crystallization dynamics of perovskite emitters and mitigating trap-mediated non-radiative losses. Specifically, we discover that the chelate effect enhances lead-additive coordination affinity, enabling the formation of thermodynamically stable intermediate phases and inhibiting halide coordination-driven perovskite nucleation. The retarded perovskite nucleation and crystal growth are key to high crystal quality and thus efficient electroluminescence. Our work elucidates the full effects of molecular additives on PeLEDs by uncovering the chelate effect as an important feature within perovskite crystallization. As such, we open new prospects for the rationalized screening of highly effective molecular additives.
|
|
| 6. |
- Zou, Yatao, et al.
(author)
-
Protocol for efficient and self-healing near-infrared perovskite light-emitting diodes.
- 2022
-
In: STAR protocols. - : Cell Press. - 2666-1667. ; 3:3
-
Journal article (peer-reviewed)abstract
- Preparation of highly efficient and stable perovskite light-emitting diodes (PeLEDs) with reproducible device performance is challenging. This protocol describes steps for fabrication of high-performance and self-healing PeLEDs. These include instructions for synthesis of charge-transporting zinc oxide (ZnO) nanocrystals, step-by-step device fabrication, and control over self-healing of the degraded devices. For complete details on the use and execution of this protocol, please refer to Teng et al. (2021).
|
|
