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S. He, W. Zhou, S.-H. Baek, K.-J. Ko, J. Luo, B.-J. Lee, H.B. Lee*, J.-H. Lee* and J.-W. Kang* "Enhanced Light Outcoupling of Perovskite Quantum Dot Light-Emitting Diodes: Significance of the Refractive Index Control of the Hole Transport Layers and the Thickness of Indium Tin Oxide" Applied Surface Science, 680, 161384 (2025)AbstractPerovskite quantum dot light-emitting diodes (PeQLEDs) are frequently considered as the most promising alternatives to organic light-emitting diodes (OLEDs). However, the efficiency of PeQLEDs remains inferior to OLEDs due to suboptimal charge carrier transport and intrinsic light outcoupling efficiency ( out). Herein, a combination of hole transport layer (HTL) engineering and substrate engineering is demonstrated to improve the charge injection and out of PeQLEDs. To replace the conventional PEDOT:PSS, a novel HTL bilayer based on modified PEDOT:PSS and PVK with a lower refractive index and fewer trap densities at the HTL-QDs interface is developed. Additionally, this study identifies the ideal thickness of ITO for achieving optimal out of PeQLEDs through optical simulations and experimental validation. Based on the synergistic use of HTL bilayer and 70-nm-thick ITO, the PeQLEDs achieved an optimal external quantum efficiency of 17.96 % at a luminance of 1763 cd/m 2 and 15.19 % at 8300 cd/m 2 without using any external outcoupling structure, indicating a low efficiency roll-off.

H.B. Lee, A. Mohamed, N. Kumar, N.H.Z. Karimy, V.V. Satale, B. Tyagi, D.-H. Kim and J.-W. Kang* "Low-Cost, Scalable Fabrication of Multi-Dimensional Perovskite Solar Cells and Modules Assisted by Mechanical Scribing" in submission (2024.6)Abstract formamidinium lead triiodide (FAPbI3) absorber are often hindered by defects at the surface and grain boundaries of the perovskite. To address this, we demonstrate the use of pyrrolidinium iodide for the in-situ formation of an energetically aligned one-dimensional (1D) pyrrolidinium lead triiodide (PyPbI3) capping layer over the 3D FAbI3 perovskite. The thermodynamically stable PyPbI3 perovskitoids, formed through cation exchange reactions, effectively reduces surface and grain boundary defects in the FAPbI3 perovskite. In addition to improved phase stability, the resulting 1D/3D perovskite film forms a cascade energy band alignment with the other functional layers in PSCs, enabling a barrier-free interfacial charge transport. With a maximum power conversion efficiency (PCE) of ~23.1% and ~20.7% at active areas of 0.09 and 1.05 cm2, respectively, the 1D/3D PSCs demonstrate excellent performance and scalability. Leveraging this improved scalability, we have successfully developed a mechanically-scribed 1D/3D perovskite mini-module with an unprecedentedly high PCE of ~20.6% and a total power output of ~270 mW at an active area of ~13.0 cm2. The 1D/3D multi-dimensional perovskite film developed herein holds great promise for producing low-cost, high-performance perovskite photovoltaics at both the cell and module levels.

Ink engineering using 1,3-dimethyl-2-imidazolidinone solvent for efficient inkjet-printed triple-cationic perovskite solar cellsAuthor links open overlay panelVinayak Vitthal Satale a, Hock Beng Lee a, Barkha Tyagi b, Manoj Mayaji Ovhal c, Sagnik Chowdhury a, Asmaa Mohamed a d, Do-Hyung Kim e, Jae-Wook Kang aHighlights Perovskite films were fabricated using a scalable inkjet printing (IJP) technique. 1,3-dimethyl-2-imidazolidinone (DMI) high boiling solvent used in perovskite ink. DMI-based IJP perovskite has a uniform, smoother film with large grains surface. IJP perovskite has a more suitable energy band alignment with SnO2 and Spiro-OMeTAD. The champion device achieved a PCE of 17.5 % and module PCE of 11.4 % (A = 12.3 cm2). AbstractInk engineering increases the quality and uniformity of large-scale perovskite films for efficient inkjet-printed perovskite solar cells (IJP-PSCs). The absorber layer in PSCs must be pinhole- and crack-free, highly uniform, with minimum defects, and have better optoelectronic properties, to improve PSC device performance. Herein, a different strategy, such as solvents with high boiling points (BPs), is used to modify the perovskite inks to obtain uniform and better-quality IJP-perovskite films. The perovskite film prepared with a 1,3-dimethyl-2-imidazolidinone (DMI) solvent is highly uniform ( 96 %), thicker, with a smoother surface, and contains bigger grains than -butyrolactone (GBL) based IJP-perovskites. The DMI solvent-based IJP-PSC device shows a greater than 17.5 % power conversion efficiency (PCE), which is much higher than that possible with GBL-based devices (PCE 13.8 %). The better performance of the IJP-PSC device is mainly due to the film s uniformity, large grains, and well-formed structures, which reduce the occurrence of specific chemical reactions within the perovskite material. The presented ink engineering strategy to develop highly uniform IJP perovskite films has the potential to be applied to perovskite solar modules. Graphical abstractA high boiling point solvent is used to engineer the perovskite ink for efficient, stable inkjet-printed perovskite solar cell (IJP-PSC) devices. The 1,3-dimethyl-2-imidazolidinone (DMI) solvent-based ink exhibited a highly uniform and smoother film, creating larger grains that resulted in efficient charge transfer to electron or hole transport layers. The DMI solvent-based IJP-PSC device showed an impressive power conversion efficiency of 17.50%, with better stability proving its potential for the scalable fabrication of inkjet-printed PSCs.https://doi.org/10.1016/j.cej.2024.152541

Congratulations!Your work stands out as one of our most widely read papers.Download this certificate of achievement celebrating your success.We are delighted to share that your work, published in Advanced Materials Interfaces , has received enough downloads to rank within the top 10% of papers published*:Complex Additive-Assisted Crystal Growth and Phase Stabilization of -FAPbIsub3/sub Film for Highly Efficient, Air-Stable Perovskite Photovoltaicshttps://doi.org/10.1002/admi.202201658

The development of anti-solvent free, scalable and printable perovskite film is crucial to realizing the low-cost roll-to-roll development of perovskite solar cells (PSCs). Herein, we explored large-area perovskite film fabrication using a spray-assisted sequential deposition technique. We investigated how propylene carbonate (PC) solvent additive affects the transformation of PbI2 into perovskite at room temperature. Our result shows that PC-modified perovskite films exhibit a uniform, pinhole-free morphology with oriented grains compared with pristine perovskite films. The PC-modified perovskite film also has a prolonged fluorescence lifetime that indicates lower carrier recombination. The champion PSC devices based on PC-modified perovskite film realized a power conversion efficiency (PCE) of 20.5% and 19.3% at an active area (A) of 0.09 cm2 and 1 cm2, respectively. The fabricated PSCs are stable and demonstrated 85% PCE retention following 60 days of exposure to ambient conditions. Furthermore, we fabricated perovskite solar modules (A ~13 cm2) that yielded a PCE of 15.8%. These results are among the best reported for the state-of-art spray-coated PSCs. Spray deposition coupled with a PC additives is highly promising for economical and high-output preparation of PSCs. https://doi.org/10.1002/smtd.202300237

Research ArticleFull AccessOne-Meter-Long, All-3D-Printed Supercapacitor Fibers Based on Structurally Engineered Electrode for Wearable Energy StorageManoj Mayaji Ovhal, Hock Beng Lee, Vinayak Vitthal Satale, Barkha Tyagi, Sagnik Chowdhury, Jae-Wook KangFirst published: 24 December 2023 https://doi-org.proxy.jbnu.ac.kr/10.1002/aenm.202303053Find it @ JBN Abstract Fiber-shaped energy storage devices have great potential for use as an intelligent power source for futuristic wearable technology. To produce high-performance fiber-shaped energy storage devices, a thin fiber material with a high energy density, shape adaptability, and longevity is critical. Herein, 3D fiber-shaped supercapacitors (SCs) comprising MXene-PEDOT:PSS active electrodes made using the 3D-direct-ink-writing (DIW) technique are demonstrated. Embedding a silver (Ag) current collector in the active electrode facilitated faster charge transport in the fiber-shaped 3D-SCs, enabling them to create a unique 3D-electrode structure that solves the thickness and length problem of electrode-dependent capacitance in fiber-shaped devices. At one-meter long, the fully-printed fiber-shaped 3D-SC exhibits a low charge transfer resistance that leads to the high areal capacitance of 1.062 F cm 2 and gravimetric capacitance of 185.9 F g 1, with a high areal energy density of 94.41 Wh cm 2 at a power density of 1,142 W cm 2. The fiber-shaped 3D-SCs also exhibit excellent electrochemical and mechanical stability at different temperatures in air and water. With their unique electrode structure and uninterrupted power supply, these R2R 3D-DIW printed fiber-shaped SCs can boost the development of innovative textile technology.

Best Post Award in PSK ConferenceSagnik ChodhuryHigh-Performance Phosphorescent Green OLEDs with a Simplified Device Structure via Substrate Surface Engineering

Formamidinium lead bromide (FAPbBr3) nanocrystals (NCs) that exhibit ultra-pure green emission are the most promising candidates for future displays. Despite the rapid development of light-emitting diodes (LEDs) based on perovskite NCs (PeNCs), there is limited research detailing their intrinsic light outcoupling. Herein, we propose the use of a short-chain fluoroaromatic ligand, 4-fluoro-phenethylammonium bromide (FPEABr) via a facile spin-casting method to fine-tune the refractive index (n) and horizontal dipole ratio values of the perovskite emitter layer and simultaneously suppress the defects formed during film deposition. After FPEABr ligand exchange, the FAPbBr3 NCs films exhibite a refractive index n significantly lower (by about 0.4) than bulk (2D/quasi 2D or 3D) perovskite films and show an enhanced value of 77%. Therefore, we successfully produce ultra-pure green PeLEDs with a maximum current efficiency of ~ 50 cd A-1, a maximum luminance of 21304 cd m-2, and a peak external quantum efficiency of 11.33% at a high luminance of 2804 cd m-2, approaching the theoretical value of 11.90% given the structure, photoluminance quantum yield, and horizontal dipole ratio. https://onlinelibrary.wiley.com/doi/10.1002/adom.202370066

Two-dimensional (2D) tin-based perovskites have gained considerable attention for use in diverse optoelectronic applications, such as solar cells, lasers, and thin-film transistors (TFTs), owing to their good stability and optoelectronic properties. However, their intrinsic charge-transport properties are limited and the insulating bulky organic ligands hinder the achievement of high-mobility electronics. Blending three-dimensional (3D) counterparts into 2D perovskites to form 2D/3D hybrid structures is a synergistic approach that combines the high mobility and stability of 3D and 2D perovskites, respectively. In this study, a reliable p-channel 2D/3D tin-based hybrid perovskite TFTs comprising 3D formamidinium tin iodide (FASnI3) and 2D fluorinated 4-fluoro-phenethylammonium tin iodide ((4-FPEA)2SnI4) are reported. The optimized FPEA-incorporated TFTs show a high hole mobility of 12 cm2 V-1 s-1, an on/off current ratio of over 108, and a subthreshold swing of 0.09 V dec-1 with negligible hysteresis. This excellent p-type characteristic is compatible with n-type metal-oxide TFT for constructing complementary electronics. Two procedures of antisolvent engineering and device patterning are further proposed to address the key concern of low performance reproducibility of perovskite TFTs. This study provides an alternative A-cation engineering method for achieving high-performance and reliable tin-halide perovskite electronics.https://doi.org/10.1002/adfm.202303309