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Quasi-2D Ruddlesden-Popper Perovskite Light-Emitters with Br-based Mixed Spacers.
이일금,임주원,전리나,( Edward H. Sargent ),김동하 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
Recently, perovskite LED has been attracting attention as a next-generation LED that can replace existing OLED and QLED. However, methylammonium lead halide (MLH) perovskite is not applicable to LED devices due to its low moisture stability. Quasi-2D perovskites (PEA)<sub>2</sub>(MA)<sub>n-1</sub>PbnBr<sub>3n+1</sub> has been reported to enhance the photoluminescence (PL) and humid-stability compared to conventional MLH 3D perovskite. However, the development of conventional ruddlesden-popper phase perovskites has been only focused on green emission region. In this regard, herein we tried to tailor the emission range of Br-based quasi-2D perovskite from green to blue region by integrating organic cation spacer. As the candidates for spacer, aromatic and aliphatic cations were employed by controlling the relative concentration ratio. As a result, the PL intensities and the emission wavelength showed emissions at blue regions. Based on our new-class of layered perovskites, we demonstrated blue-region LED devices.
Dimensionality-Tailored Quasi-2D Perovskites for Highly Stable and Efficient Photodetectors
임주원,( Huan Wang ),( Li Na Quan ),( Edward H. Sargent ),김동하 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
In this work, we developed perovskite photodetector devices by integ-rating dimension-reduced (quasi-2D) perovskites instead of conven-tional three-dimensional counterparts. A series of quasi-2D perovskite films were synthesized to obtain advanced photodectors with improved stability while retaining the comparable electrical perform-ance of conventional three-dimensional perovskites. The quasi-2D perovskite photodetector exhibited a responsivity of 0.53 A/W and detectivity of 2.20ⅹ1012 J, which is attributed to decreased leakage current. In addition, the current density of quasi-2D perovskite photo-detector maintained 76 % while three-dimensional perovskite photodetector remained only 15 % of initial level after 2,000 hours. We confirm the stability of perovskite films via X-ray diffraction (XRD) and atomic force microscope (AFM) measurement.
Self-Assembled PbSe Nanowire:Perovskite Hybrids
Yang, Zhenyu,Yassitepe, Emre,Voznyy, Oleksandr,Janmohamed, Alyf,Lan, Xinzheng,Levina, Larissa,Comin, Riccardo,Sargent, Edward H. American Chemical Society 2015 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.137 No.47
<P>Inorganic semiconductor nanowires are of interest in nano- and microscale photonic and electronic applications. Here we report the formation of PbSe nanowires based on directional quantum dot alignment and fusion regulated by hybrid organic–inorganic perovskite surface ligands. All material synthesis is carried out at mild temperatures. Passivation of PbSe quantum dots was achieved via a new perovskite ligand exchange. Subsequent <I>in situ</I> ammonium/amine substitution by butylamine enables quantum dots to be capped by butylammonium lead iodide, and this further drives the formation of a PbSe nanowire superlattice in a two-dimensional (2D) perovskite matrix. The average spacing between two adjacent nanowires agrees well with the thickness of single atomic layer of 2D perovskite, consistent with the formation of a new self-assembled semiconductor nanowire:perovskite heterocrystal hybrid.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2015/jacsat.2015.137.issue-47/jacs.5b10641/production/images/medium/ja-2015-106416_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja5b10641'>ACS Electronic Supporting Info</A></P>
Challenges for commercializing perovskite solar cells
Rong, Yaoguang,Hu, Yue,Mei, Anyi,Tan, Hairen,Saidaminov, Makhsud I.,Seok, Sang Il,McGehee, Michael D.,Sargent, Edward H.,Han, Hongwei American Association for the Advancement of Scienc 2018 Science Vol.361 No.6408
<P>Perovskite solar cells (PSCs) have witnessed rapidly rising power conversion efficiencies, together with advances in stability and upscaling. Despite these advances, their limited stability and need to prove upscaling remain crucial hurdles on the path to commercialization. We summarize recent advances toward commercially viable PSCs and discuss challenges that remain. We expound the development of standardized protocols to distinguish intrinsic and extrinsic degradation factors in perovskites. We review accelerated aging tests in both cells and modules and discuss the prediction of lifetimes on the basis of degradation kinetics. Mature photovoltaic solutions, which have demonstrated excellent long-term stability in field applications, offer the perovskite community valuable insights into clearing the hurdles to commercialization.</P>
Synergistic photocurrent addition in hybrid quantum dot: Bulk heterojunction solar cells
Kim, Gi-Hwan,Walker, Bright,Zhitomirsky, David,Heo, Jungwoo,Ko, Seo-Jin,Park, Jongnam,Sargent, Edward H.,Young Kim, Jin Elsevier 2015 Nano energy Vol.13 No.-
<P><B>Abstract</B></P> <P>We investigate the effect of a thin PbS quantum dot (QD) layer on the performance of hybrid quantum-dot-organic solar cells (QD-OSCs). The PbS QD layer is able to function as a photosensitizing layer to improve short circuit current density (<I>J</I> <SUB>SC</SUB>) and power conversion efficiency (PCE) by exploiting solar flux in the near infrared region up to 1100nm. The increase in <I>J</I> <SUB>SC</SUB> is well represented by changes observed in the external quantum efficiency of devices with and without the PbS QD layer, including the region of the first exciton transition where only the PbS QD layer absorbs. Remarkably, enhanced performance was observed in QD-OSCs consisting of just a 13nm thick PbS QD layer and 150nm PTB7:PC<SUB>71</SUB>BM layer, exhibiting a <I>J</I> <SUB>SC</SUB> of 17.0mAcm<SUP>−2</SUP>, and PCE of 8.30% (8.58% for champion device) compared to reference devices without PbS QD which produced a <I>J</I> <SUB>SC</SUB> of 15.4mAcm<SUP>−2</SUP> and PCE of 7.56%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We have fabricated hybrid solar cells using a PbS QD layer and PTB7/PC<SUB>71</SUB>BM layer. </LI> <LI> The device is built on PTB7:PC<SUB>71</SUB>BM bulk heterojunction and a PbS QD layer. </LI> <LI> The PbS QD layer acts as a photosensitizing layer to improve the device performance. </LI> <LI> Additional photocurrent leads to enhancement in performance in hybrid solar cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>The effect of a thin PbS quantum dot (QD) layer on the performance of hybrid quantum-dot-organic solar cells (QD-OSCs) was investigated. The PbS QD layer is able to function as a photosensitizing layer with PTB7/PC<SUB>71</SUB>BM bulk heterojunction to improve short circuit current density from 15.4mAcm<SUP>−2</SUP> to 17.0mAcm<SUP>−2</SUP> and power conversion efficiency from 7.56% to 8.30%. </P> <P>[DISPLAY OMISSION]</P>