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Recent Progress in Inorganic Hole Transport Materials for Efcient and Stable Perovskite Solar Cells
Bumjin Gil,Alan Jiwan Yun,Younghyun Lee,Jinhyun Kim,Byungho Lee,Byungwoo Park 대한금속·재료학회 2019 ELECTRONIC MATERIALS LETTERS Vol.15 No.5
Organic–inorganic hybrid perovskite solar cells (PSCs) are considered as one of the most promising emerging photovoltaicswith outstanding performance. However, the commonly used organic hole transport materials (HTMs) suffer fromheat-, light-, and bias-induced degradation along with defect diffusion and hygroscopic properties. To resolve these issuesin conventional HTMs, inorganic materials with superior chemical stability, high carrier mobility, and low cost have beendeveloped, demonstrating improved stability under rigorous conditions such as high temperature and long-term illumination. Understanding the properties of alternative inorganic HTMs is of prominent importance to realize more stable and efficientPSCs. This review summarizes the recent progresses in inorganic HTMs adopted in various device architectures, with theirremarkable achievements in efficiency and long-term stability.
Selective rear contact for Ga<sub>0.5</sub>In<sub>0.5</sub>P- and GaAs- based solar cells
Hwang, Sun-Tae,Hwang, Taehyun,Lee, Sangheon,Gil, Bumjin,Park, Byungwoo Elsevier 2018 Solar energy materials and solar cells Vol.182 No.-
<P><B>Abstract</B></P> <P>The light management strategy was applied in III-V solar cells for the maximum utilization of incident photon, namely the selective rear contact was adopted in Ga<SUB>0.5</SUB>In<SUB>0.5</SUB>P- and GaAs- based solar cells. By etching the rear contact layer (<I>p</I>-GaAs) with photolithography, the distinctive morphological structures consisting of polka-dot patterns were formed, which led to increased reflection and thereby the device performance. Furthermore, the photolithography was controlled to find the optimum contact ratio between the back-surface field and the rear contact. Consequently, the conversion efficiency was increased from <I>η</I> = 15.5% to 16.3% for the Ga<SUB>0.5</SUB>In<SUB>0.5</SUB>P-based single-junction solar cell, and from <I>η</I> = 21.1% to 21.9% for the GaAs-based one, both at the contact ratio of 10%, compared to the cells with full (100%) rear contact ratio. Finally, the selective rear contact was applied to double-junction solar cells (Ga<SUB>0.5</SUB>In<SUB>0.5</SUB>P- and GaAs- based), exhibiting that this straightforward rear-contact strategy has enabled reaching the efficiency of <I>η</I> = 30.6% with an anti-reflective coating.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Selective rear contact was applied for maximum utilization of incident photon. </LI> <LI> Polka-dot rear-contact patterns were facilely structured by photolithography. </LI> <LI> The efficiency of Ga<SUB>0.5</SUB>In<SUB>0.5</SUB>P- and GaAs- based double-junction cell reached <I>η</I> = 30.6%. </LI> </UL> </P>
Lee, Sangheon,Flanagan, Joseph C.,Lee, Byungho,Hwang, Taehyun,Kim, Jaewook,Gil, Bumjin,Shim, Moonsub,Park, Byungwoo American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.37
<P>One-dimensionally elongated nanoparticles with type-II staggered band offset are of potential use as light-harvesting materials for photovoltaics, but only a limited attention has been given to elucidate the factors governing the cell performance obtainable from such materials. Herein, we describe a combined strategy to enhance charge collection from CdSe/CdSexTe1-x type-II heterojunction nanorods (HNRs) utilized as light harvesters for sensitized solar cells. By integrating morphology- and composition-tuned type-II HNRs into solar cells, factors that yield interfaces favorable both for the electron injection into TiO2 and hole transfer to electrolyte are examined. Furthermore, it is shown that a more efficient photovoltaic system results from cosensitization with CdS quantum dots (QDs) predeposited on a TiO2 scaffold, which improves charge collection from HNRs. Electrochemical impedance spectroscopy (EIS) analysis suggests that such a synergistically enhanced system benefits from the decreased recombination within HNRs and facilitated charge transport through the cosensitized TiO2 electrode, even with the activation of a recombination path presumably related to the photogenerated holes in CdS QDs.</P>
Multifunctional Green Solvent for Efficient Perovskite Solar Cells
Jaemin Cho,Beomsoo Kim,Seokjoo Ryu,Alan Jiwan Yun,Bumjin Gil,Jiheon Lim,Jihyun Kim,Jinhyun Kim,Byungwoo Park 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.5
Organometal trihalide perovskite has recently been considered as one of the leading candidates to achieve highly effi cient perovskite solar cells (PSCs). However, current PSC procedures commonly rely on the large volume of highly toxic halogenated or highly fl ammable solvents which are not favorable for the large-scale commercialization of PSCs. Herein, we employ nontoxic and nonhalogenated salicylaldehyde from the buckwheat as a both nonpolar (antisolvent) and polar (posttreatmentdissolving) solvent for the multifunctional purpose. Salicylaldehyde has a semipolar characteristic due to the hydroxyl group (–OH) attached to the benzene ring, enabling it to utilize both polar and nonpolar solvents in the PSCs fabrications. As a result, the PSC using green solvent achieved a power conversion effi ciency (PCE) up to 20.23%. Encapsulated devices retained over 80% of their initial PCE, after ~ 750 h of constant 1-sun illumination, and after ~ 1100 h under 60 °C heat. Overall, this work demonstrates that salicylaldehyde can be an alternative solvent for green and effi cient fabrication in the PSC.
Wi, Sungun,Park, Jungjin,Lee, Sangheon,Kim, Jaewon,Gil, Bumjin,Yun, Alan Jiwan,Sung, Yung-Eun,Park, Byungwoo,Kim, Chunjoong Elsevier 2017 Nano energy Vol.39 No.-
<P><B>Abstract</B></P> <P>The kinetic processes during delithiation/lithiation of Li<SUB> <I>x</I> </SUB>Mn<SUB>0.8</SUB>Fe<SUB>0.2</SUB>PO<SUB>4</SUB> are thoroughly investigated through <I>operando</I> x-ray diffraction and <I>in situ</I> electrochemical impedance spectroscopy combined with galvanostatic intermittent titration technique (GITT), by which new insights on the phase propagation and sluggish kinetics of LiMn<SUB>0.8</SUB>Fe<SUB>0.2</SUB>PO<SUB>4</SUB> (LMFP) cathode materials are elaborated. <I>In situ</I> analyses on the solvothermally synthesized carbon-coated LMFP mesocrystals reveal that the phase-propagation mechanisms differ during delithiation/lithiation processes, and the sluggish kinetics of LMFP followed by the limitation of achievable (dis)charge capacities originate from the poor apparent Li<SUP>+</SUP> diffusivity, which is triggered by Mn redox reaction. Based on the in-depth characterization of the reaction kinetics in LMFP mesocrystals, our work provides fundamental understanding to design high-performance Mn-based olivine cathodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> LiMn<SUB>0.8</SUB>Fe<SUB>0.2</SUB>PO<SUB>4</SUB> mesocrystals synthesized by a straightforward solvothermal method. </LI> <LI> Superior electrochemical properties (i.e., high specific capacity and rate capability). </LI> <LI> Fundamental understanding on the reaction kinetics of LMFP by <I>in situ</I> techniques. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Woo, Hyungsub,Wi, Sungun,Kim, Jaewon,Kim, Jinhyun,Lee, Sangheon,Hwang, Taehyun,Kang, Joonhyeon,Kim, Jaewook,Park, Kimin,Gil, Bumjin,Nam, Seunghoon,Park, Byungwoo Elsevier 2018 Carbon Vol.129 No.-
<P><B>Abstract</B></P> <P>Among the efforts to apply SnO<SUB>2</SUB> as an anode, the adoption of carbonaceous materials has been considered as a decent strategy to mitigate volume expansion problem (∼300%) during cycling. Nevertheless, it still needs in-depth examinations to identify the individual role of each coating material and further improvements for practical applications. To understand the underlying correlations of various carbon coatings with electrochemical performance of active materials, disordered carbon and reduced graphene oxide (RGO) are selectively used for SnO<SUB>2</SUB> hollow spheres. The disordered carbon, which covered the surfaces of and voids between the primary particles, acts as a buffer layer for volume expansion, and the RGO, that interconnected the hollow secondary particles, provides a 2D-electronic path to the electrode. Finally, both of them are utilized on the SnO<SUB>2</SUB> hollow spheres, namely the double coating is conducted from the expectation of synergistic effects, and it successfully exhibits a moderate capacity after 100 cycles even at 1 C with a low carbon content (7.7 wt. %). The essential factors that are inherently present and thereby significantly affect the electrochemical performance of the SnO<SUB>2</SUB> electrode are successfully identified by a facile dual-carbon modification, so that this strategy will be applicable to other potential active materials.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>