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Single-emissive-layer all-perovskite white light-emitting diodes employing segregated mixed halide perovskite crystals
Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.ORCID-id: 0000-0003-3024-9838
Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.ORCID-id: 0000-0002-9840-7364
Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.ORCID-id: 0000-0001-5220-9779
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2020 (Engelska)Ingår i: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 11, nr 41, s. 11338-11343Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Metal halide perovskites have demonstrated impressive properties for achieving efficient monochromatic light-emitting diodes. However, the development of white perovskite light-emitting diodes (PeLEDs) remains a big challenge. Here, we demonstrate a single-emissive-layer all-perovskite white PeLED using a mixed halide perovskite film as the emissive layer. The perovskite film consists of separated mixed halide perovskite phases with blue and red emissions, which are beneficial for suppressing halide anion exchange and preventing charge transfer. As a result, the white PeLED shows balanced white light emission with Commission Internationale de L'Eclairage coordinates of (0.33, 0.33). In addition, we find that the achievement of white light emission from mixed halide perovskites strongly depends on effective modulation of the halide salt precursors, especially lead bromide and benzamidine hydrochloride in our case. Our work provides very useful guidelines for realizing single-emissive-layer all-perovskite white PeLEDs based on mixed halide perovskites, which will spur the development of high-performance white PeLEDs.

Ort, förlag, år, upplaga, sidor
Royal Society of Chemistry, 2020. Vol. 11, nr 41, s. 11338-11343
Nationell ämneskategori
Den kondenserade materiens fysik
Identifikatorer
URN: urn:nbn:se:liu:diva-171233DOI: 10.1039/D0SC04508JISI: 000582936200023Scopus ID: 2-s2.0-85094850888OAI: oai:DiVA.org:liu-171233DiVA, id: diva2:1500196
Anmärkning

Funding agencies: ERC Starting Grant (717026), Swedish Energy Agency Energimyndigheten (no. 48758-1), Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU no. 2009-00971), China Scholarship Council

Tillgänglig från: 2020-11-11 Skapad: 2020-11-11 Senast uppdaterad: 2021-12-28
Ingår i avhandling
1. Color Tuning for Perovskite Light-Emitting Diodes
Öppna denna publikation i ny flik eller fönster >>Color Tuning for Perovskite Light-Emitting Diodes
2020 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Metal halide perovskites (MHPs) are recognized as promising semiconductor materials for a variety of optical and electrical device applications due to their cost-effective and outstanding optoelectronic properties. As one of the most significant applications, perovskite light-emitting diodes (PeLEDs) hold promise for future lighting and display technologies, attributed to their high photoluminescence quantum yield (PLQY), high color purity, and tunable emission color. The emission colors of PeLEDs can be tuned by mixing the halide anions, adjusting the size of perovskite nanocrystals, or changing the dimensionality of perovskites. However, in practice, all these different approaches have their own advantages and challenges. This thesis centres around the color tunability of perovskites, aiming to develop PeLEDs with different colors using different approaches.

We first demonstrate red and near-infrared PeLEDs using a straightforward approach – in situ solution-processed perovskite quantum dots (PQDs). PQDs prepared from colloidal approaches are widely reported and used in LEDs. In contrast, PQDs prepared from the in situ approaches are hardly reported, although they have advantages for device applications. By employing aromatic ammonium iodide (1-naphthylmethyl ammonium iodide, NMAI) as an agent into perovskite precursor solutions, together with annealing temperature modulation, we obtain in situ grown PQDs delivering high external quantum efficiencies (EQEs) of up to 11.0% with tunable electroluminescence (EL) spectra (667 - 790 nm). Our in situ generated PQDs based on pure-halogen perovskites can be easily obtained through a simple deposition process and free of phase segregation, making them a more promising approach for tuning the emission colors of perovskite LEDs.

We then move to blue PeLEDs using cesium-based mixed-Br/Cl perovskites. Although mixed halides are a straightforward strategy to tune the emission color, PeLEDs based on this approach suffer from poor color stability, which is attributed to surface defects at grain boundaries. Under the condition of optical excitations, light density over a certain value (a threshold), oxygen, and surface defects at perovskite grain boundaries are found to be key factors inducing photoluminescence (PL) spectral instability of CsPb(Br1−xClx)3 perovskites. Upon electrical bias, defects at grain boundaries provide undesirable halide migration channels, responsible for EL spectral instability issues. Through effective defect passivation, the PL spectral resistance to oxygen is enhanced; moreover, high-performance and color-stable blue PeLEDs are achieved, delivering a maximum luminance of 5351 cd m–2 and a peak EQE of 4.55% with a peak emission wavelength at 489 nm. These findings provide new insights into the color instability issue of mixed halide blue perovskites, against which we also demonstrate an effective strategy.

We finally realize single-emissive-layer (EML) white PeLEDs by employing a mixed halide perovskite film as the EML. In spite of high-performance monochromatic blue, green, and red colors, the development of white PeLEDs, especially for single-EML ones, remains a very big challenge. By effective modulation of the halide salt precursors, we achieve single-EML white PeLEDs with Commission Internationale de L’Eclairage (CIE) coordinates of (0.33, 0.33), close to those (0.3128, 0.3290) of the CIE standard illuminant D65. This work not only provides a successful demonstration of a single-EML white PeLED, but also provides useful guidelines for the future development of highperformance single-EML white PeLEDs.

Ort, förlag, år, upplaga, sidor
Linköping: Linköping University Electronic Press, 2020. s. 72
Serie
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 2089
Nyckelord
Perovskite light-emitting diodes, Color tuning, Pure and mixed halide, Spectral stability, White emission
Nationell ämneskategori
Den kondenserade materiens fysik
Identifikatorer
urn:nbn:se:liu:diva-171237 (URN)10.3384/diss.diva-171237 (DOI)9789179298098 (ISBN)
Disputation
2020-11-12, Online through Zoom (contact ann-charlotte.svensson@liu.se) and ACAS, A Building, Campus Valla, Linköping, 09:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2020-11-11 Skapad: 2020-11-11 Senast uppdaterad: 2020-11-16Bibliografiskt granskad

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Yu, HonglingWang, HeyongPozina, GaliaYin, ChunyangLiu, Xiao-KeGao, Feng

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