Dae-Yong Son - Academia.edu (original) (raw)

Papers by Dae-Yong Son

Research paper thumbnail of A solid–liquid hybrid electrolyte for lithium ion batteries enabled by a single-body polymer/indium tin oxide architecture

Journal of Physics D: Applied Physics

Solid-state electrolytes have received much attention because of their high safety and cycling st... more Solid-state electrolytes have received much attention because of their high safety and cycling stability for lithium ion batteries. However, the interfacial contact issue of solid electrolytes with the electrode and active material hinders their practical use. Herein, for the first time, we demonstrate a hybrid electrolyte that combines a solid polyethylene terephthalate (PET) electrolyte with an organic liquid electrolyte to provide synergetic benefits over a single electrolyte. The single-body PET electrolyte/In2O3–SnO2 (ITO; 110 nm, 150 nm, 260 nm and 340 nm) electrode was prepared by vacuum sputtering deposition. The simplicity of the electrode composite (e.g., conductive additive-free, solvent-free and binder-free) and its gapless structure between the polymer substrate and the active material significantly impede the formation of by-products from the decomposed electrolyte as well as the growth of an unstable solid electrolyte interphase upon cycling. In addition, the cell con...

Research paper thumbnail of Rapid hybrid chemical vapor deposition for efficient and hysteresis-free perovskite solar modules with an operation lifetime exceeding 800 hours

Journal of Materials Chemistry A, 2020

Rapid hybrid chemical vapor deposition is developed to fabricate perovskite solar modules with a ... more Rapid hybrid chemical vapor deposition is developed to fabricate perovskite solar modules with a markedly reduced time while maintaining high performance.

Research paper thumbnail of Effects of Seed Layer on Growth of ZnO Nanorod and Performance of Perovskite Solar Cell

The Journal of Physical Chemistry C, 2015

ABSTRACT Effects of seed layer on growth of ZnO nanorod and photovoltaic performance of perovskit... more ABSTRACT Effects of seed layer on growth of ZnO nanorod and photovoltaic performance of perovskite solar cell were investigated. Three different coating solutions (the clear solution, the colloidal solution and the nano-powder dispersed solution) were prepared for making seed layers. Vertically aligned ZnO nanorods were grown on the colloidal-based seed layer, while tilted nanorods were obtained on the solution- and powder-based seed layers. Open-circuit voltage (Voc) of the CH3NH3PbI3 perovskite solar cell was predominantly influenced by the seed layers, where highest Voc was obtained from the ZnO nanorod grown on the colloidal seed layer. Impedance spectroscopic study revealed that recombination resistances at the seed layer contact and the ZnO nanorod/perovskite interface were increased by the colloidal coating, which was responsible for the enhanced Voc. Surface modification of ZnO nanorods improved further Voc and fill factor, leading to power conversion efficiency of 14.35%. This work emphasizes that the seed layer in the ZnO nanorod-based perovskite solar cell play major role in determining photovoltage and the ZnO nanorod/perovskite interface get involved partly in this role.

Research paper thumbnail of 11% Efficient Perovskite Solar Cell Based on ZnO Nanorods: An Effective Charge Collection System

The Journal of Physical Chemistry C, 2014

A perovskite solar cell based on ZnO nanorods was prepared, and its photovoltaic performance was ... more A perovskite solar cell based on ZnO nanorods was prepared, and its photovoltaic performance was investigated. ZnO nanorods were grown on the ZnO seed layer from solution, and their diameters and lengths were controlled by precursor concentration and growth time. CH 3 NH 3 PbI 3 perovskite infiltrated ZnO nanorods showed a power conversion efficiency of 11.13% with short-circuit current density J sc of 20.08 mA/cm 2 , open-circuit voltage V oc of 991 mV and fill factor of 0.56. Square spectral feature of external quantum efficiency (EQE) was observed, where EQE exceeded 80% in almost the entire wavelength range from 400 to 750 nm, and the integrated current density of 20.03 mA/cm 2 calculated from EQE data was in good agreement with the observed J sc. Compared to the perfect spectral response of ZnO nanorods, a perovskite solar cell based on TiO 2 nanorods exhibited an integrated current density (16 mA/cm 2) much lower than the measured J sc (20.9 mA/cm 2). In addition, time-limited photocurrent response under 530 and 700 nm monochromatic beams at 10 Hz showed that device signal amplitude, associated with charge collection, was rapidly saturated for the ZnO nanorod-based device whereas charge collection was not fully detected for the TiO 2 nanorod-based device because of slow collection rate. The current results suggest that ZnO nanorod is an effective charge collection system in CH 3 NH 3 PbI 3 based perovskite solar cells.

Research paper thumbnail of Hierarchical SnO 2 Nanoparticle-ZnO Nanorod Photoanode for Improving Transport and Life Time of Photoinjected Electrons in Dye-Sensitized Solar Cell

ACS Applied Materials & Interfaces, 2013

A hierarchical photoanode comprising a SnO(2) nanoparticle underlayer and a ZnO nanorod overlayer... more A hierarchical photoanode comprising a SnO(2) nanoparticle underlayer and a ZnO nanorod overlayer was prepared and its photovoltaic performance was compared to photoanodes consisting of SnO(2) nanoparticle only and ZnO nanorod only. The photoanode layer thickness was adjusted to about 7.6 μm to eliminate thickness effect. Ruthenium complex, coded N719, was used as a sensitizer. The photoanode composed of ZnO nanorod only showed a power conversion efficiency (PCE) as low as 0.54% with a short-circuit photocurrent density (J(SC)) of 2.04 mA/cm(2) and an open-circuit voltage (V(OC)) of 500 mV. The photoanode with SnO(2) nanoparticle only exhibited higher PCE (1.24%) because of higher J(SC) (6.64 mA/cm(2)), whereas V(OC) (340 mV) was lower than ZnO nanorod. Compared to SnO(2) nanoparticle and ZnO nanorod films, the bilayer structured film demonstrated much higher PCE (2.62%) because of both higher J(SC) (7.35 mA/cm(2)) and V(OC) (660 mV). Introduction of ZnO nanorod on the SnO(2) nanoparticle layer improved significantly electron transport and lifetime compared to the SnO(2) only film. One Order of magnitude slower charge recombination rate for the bilayer film than for the SnO(2) film was mainly responsible for the improved efficiency.

Research paper thumbnail of Quantum-Dot-Sensitized Solar Cell with Unprecedentedly High Photocurrent

Scientific Reports, 2013

The reported photocurrent density (J SC) of PbS quantum dot (QD)-sensitized solar cell was less t... more The reported photocurrent density (J SC) of PbS quantum dot (QD)-sensitized solar cell was less than 19 mA/ cm 2 despite the capability to generate 38 mA/cm 2 , which results from inefficient electron injection and fast charge recombination. Here, we report on a PbS:Hg QD-sensitized solar cell with an unprecedentedly high J SC of 30 mA/cm 2. By Hg 21 doping into PbS, J SC is almost doubled with improved stability. Femtosecond transient study confirms that the improved J SC is due to enhanced electron injection and suppressed charge recombination. EXAFS reveals that Pb-S bond is reinforced and structural disorder is reduced by interstitially incorporated Hg 21 , which is responsible for the enhanced electron injection, suppressed recombination and stability. Thanks to the extremely high J SC , power conversion efficiency of 5.6% is demonstrated at one sun illumination. Q uantum dot (QD, semiconductor nanocrystal) has been recently drawing great attention as a material for solar energy conversion due to high absorption coefficient, tunable band gap and multiple exciton generation (MEG) effect 1-4. QDs have been actively studied in dye-sensitized solar cell (DSSC) as alternatives to conventional organic dyes 5. As a result, remarkable accomplishments have been achieved in recent year, where a power conversion efficiency (PCE) of ca. 5% was achieved using metal chalcogenides 6,7 and around 10% using organic-inorganic perovskite 8. However, most of the studied QDs for DSSC were based on the relatively large band gap materials (.1.5 eV) 6-8. Using these materials, it may not be possible to utilize the full solar spectrum, which leads to a limited short-circuit photocurrent density (J SC) of ca. 20 mA/cm 2 (considering 20% loss from FTO glass) 9. No successful examples have been reported on high J SC QD-sensitized solar cells based on low band gap QDs (,1.5 eV) although it has ability to generate extremely high J SC owing to near IR absorption. Among the various low band gap QDs, PbS is one of the most intensively studied low band gap semiconductors since it has a high absorption coefficient of 1,5310 5 cm 21 and wide range of tunable band gap owing to its large bohr exciton radius of 18 nm 10,11. There have been a lot of efforts to use the PbS QD as a sensitizer. Antonio Braga et al. demonstrated a PCE of 2.21% with J SC of 10.91 mA/cm 2 using PbS/CdS QD photoelectrode being in contact with polysulfide electrolyte 12. Very recently, it was enhanced to 3.82% with J SC of 18.84 mA/cm 2 by incorporating PbS/CdS QD in hierarchical porous TiO 2 13. However, the observed J SC s are still far below the theoretical value of 38 mA/cm 2 (after considering 20% light reflection at FTO) when considering the band gap of ca. 1.0 eV 9. Main drawback of PbS QD in QD-sensitized solar cell has been argued to be inefficient charge separation and collection due to slow electron transfer kinetics 14. Electron injection from the conduction band of PbS QD to the conduction band of TiO 2 was measured to be a ca. 100 ns, which is five times slower than CdSe QD (20 ns from colloidal in organic solvent) 14. In addition, it was also argued that PbS QD served as critical recombination center, which means that injected electrons in conduction band of TiO 2 tends to recombine readily with positively charged PbS QD, and thereby efficient charge collection was seriously impeded 12,15. For efficient charge separation and collection from the PbS QD, injection and recombination kinetics of PbS QD must be tuned. However, little attempt has been made to date. Here, we report on a QD-sensitized solar cell with J SC approaching 30 mA/cm 2 based on PbS:Hg QDs. Deposition of PbS:Hg QD on nanostructured TiO 2 is implemented by simple wet chemical process, where the photovoltaic performance is evaluated by using polysulfide as a redox electrolyte. Noticeable conversion efficiency of 5.6% with unprecedented high J SC is demonstrated under AM 1.5G one sun illumination. Electron injection and charge recombination kinetics are studied by femtosecond transient absorption measurements.

Research paper thumbnail of A Preponderant Enhancement of Conversion Efficiency by Surface Coating of SnO₂ Nanoparticles in Organic MK-2 Dye Sensitized Solar Cell

Nanocrystalline SnO2 colloids are synthesized by hydrolysis of SnCl4·5H2O in aqueous ammonia solu... more Nanocrystalline SnO2 colloids are synthesized by hydrolysis of SnCl4·5H2O in aqueous ammonia solution. The synthesized SnO2 nanoparticles with ca. 15 nm in diameter are coated on a fluorinedoped thin oxide (FTO) conductive substrate and heated at 550C. The annealed SnO2 film is treated with aqueous TiCl4 solution, which is sensitzied with MK-2 dye (2-cyano-3-[5'''-(9-ethyl9H-carbazol-3-yl)-3',3'',3''',4-tetra-n-hexyl-[2,2',5',2'',5'',2''']-quater thiophen-5-yl]). Compared to bare SnO2 film, the conversion efficiency is significantly improved from 0.22% to 3.13% after surface treatment of SnO2 with TiCl4, which is mainly due to the large increases in both photocurrent density from 1.33 to 9.46 mA/cm and voltage from 315 to 634 mV. It is noted that little change in the amount of the adsorbed dye is detected from 1.21 for the bare SnO2 to 1.28 μmol/cm for the TiCl4treated SnO2. This indicates that the photocurrent ...

Research paper thumbnail of Scalable Fabrication of >90 cm 2 Perovskite Solar Modules with >1000 h Operational Stability Based on the Intermediate Phase Strategy

Advanced Energy Materials

Research paper thumbnail of Removal of residual compositions by powder engineering for high efficiency formamidinium-based perovskite solar cells with operation lifetime over 2000 h

Research paper thumbnail of A holistic approach to interface stabilization for efficient perovskite solar modules with over 2,000-hour operational stability

Research paper thumbnail of 2D Derivative Phase Induced Growth of 3D All Inorganic Perovskite Micro–Nanowire Array Based Photodetectors

Advanced Functional Materials

Research paper thumbnail of The Impact of Atmosphere on Energetics of Lead Halide Perovskites

Advanced Energy Materials

Research paper thumbnail of Inverse Growth of Large-Grain-Size and Stable Inorganic Perovskite Micronanowire Photodetectors

ACS Applied Materials & Interfaces

Research paper thumbnail of Imaging of the Atomic Structure of All-Inorganic Halide Perovskites

The Journal of Physical Chemistry Letters

Research paper thumbnail of Water splitting exceeding 17% solar-to-hydrogen conversion efficiency using solution-processed Ni base electrocatalysts and perovskite/Si tandem solar cell

ACS Applied Materials & Interfaces

Research paper thumbnail of Carbon-based Electrode Engineering Boosts the Efficiency of All Low-temperature Processed Perovskite Solar Cells

Research paper thumbnail of 1D Hexagonal HC(NH2 )2 PbI3 for Multilevel Resistive Switching Nonvolatile Memory

Advanced Electronic Materials

Research paper thumbnail of Hybrid Chemical Vapor Deposition Enables Scalable and Stable Cs-FA Mixed Cation Perovskite Solar Modules with a Designated Area of 91.8 cm2 Approaching 10% Efficiency

Journal of Materials Chemistry A

The development of scalable deposition methods for stable perovskite layer is a prerequisite for ... more The development of scalable deposition methods for stable perovskite layer is a prerequisite for the development and the future commercialization of perovskite solar modules. However, scalability and stability are the...

Research paper thumbnail of Negligible-Pb-Waste and Upscalable Perovskite Deposition Technology for High-Operational-Stability Perovskite Solar Modules

Advanced Energy Materials

Over the past few years, there have been unprecedented advances in solar cells using metal halide... more Over the past few years, there have been unprecedented advances in solar cells using metal halide perovskite materials as light absorbers. [1-3] A record power conversion efficiency An upscalable perovskite film deposition method combining raster ultrasonic spray coating and chemical vapor deposition is reported. This method overcomes the coating size limitation of the existing stationary spray, single-pass spray, and spin-coating methods. In contrast with the spin-coating method (>90% Pb waste), negligible Pb waste during PbI 2 deposition makes this method more environmentally friendly. Outstanding film uniformity across the entire area of 5 cm × 5 cm is confirmed by both large-area compatible characterization methods (electroluminescence and scattered light imaging) and local characterization methods (atomic force microscopy, scanning electron microscopy, photoluminescence mapping, UV-vis, and X-ray diffraction measurements on multiple sample locations), resulting in low solar cell performance decrease upon increasing device area. With the FAPb(I 0.85 Br 0.15) 3 (FA = formamidinium) perovskite layer deposited by this method, champion solar modules show a power conversion efficiency of 14.7% on an active area of 12.0 cm 2 and an outstanding shelf stability (only 3.6% relative power conversion efficiency decay after 3600 h aging). Under continuous operation (1 sun light illumination, maximum power point condition, dry N 2 atmosphere with <5% relative humidity, no encapsulation), the devices show high light-soaking stability corresponding to an average T 80 lifetime of 535 h on the small-area solar cells and 388 h on the solar module.

Research paper thumbnail of Lithium-ion batteries: outlook on present, future, and hybridized technologies

Journal of Materials Chemistry A

Lithium-ion batteries (LIBs) continue to draw vast attention as a promising energy storage techno... more Lithium-ion batteries (LIBs) continue to draw vast attention as a promising energy storage technology due to their high energy density, low self-discharge property, nearly zero-memory effect, high open circuit voltage,...

Research paper thumbnail of A solid–liquid hybrid electrolyte for lithium ion batteries enabled by a single-body polymer/indium tin oxide architecture

Journal of Physics D: Applied Physics

Solid-state electrolytes have received much attention because of their high safety and cycling st... more Solid-state electrolytes have received much attention because of their high safety and cycling stability for lithium ion batteries. However, the interfacial contact issue of solid electrolytes with the electrode and active material hinders their practical use. Herein, for the first time, we demonstrate a hybrid electrolyte that combines a solid polyethylene terephthalate (PET) electrolyte with an organic liquid electrolyte to provide synergetic benefits over a single electrolyte. The single-body PET electrolyte/In2O3–SnO2 (ITO; 110 nm, 150 nm, 260 nm and 340 nm) electrode was prepared by vacuum sputtering deposition. The simplicity of the electrode composite (e.g., conductive additive-free, solvent-free and binder-free) and its gapless structure between the polymer substrate and the active material significantly impede the formation of by-products from the decomposed electrolyte as well as the growth of an unstable solid electrolyte interphase upon cycling. In addition, the cell con...

Research paper thumbnail of Rapid hybrid chemical vapor deposition for efficient and hysteresis-free perovskite solar modules with an operation lifetime exceeding 800 hours

Journal of Materials Chemistry A, 2020

Rapid hybrid chemical vapor deposition is developed to fabricate perovskite solar modules with a ... more Rapid hybrid chemical vapor deposition is developed to fabricate perovskite solar modules with a markedly reduced time while maintaining high performance.

Research paper thumbnail of Effects of Seed Layer on Growth of ZnO Nanorod and Performance of Perovskite Solar Cell

The Journal of Physical Chemistry C, 2015

ABSTRACT Effects of seed layer on growth of ZnO nanorod and photovoltaic performance of perovskit... more ABSTRACT Effects of seed layer on growth of ZnO nanorod and photovoltaic performance of perovskite solar cell were investigated. Three different coating solutions (the clear solution, the colloidal solution and the nano-powder dispersed solution) were prepared for making seed layers. Vertically aligned ZnO nanorods were grown on the colloidal-based seed layer, while tilted nanorods were obtained on the solution- and powder-based seed layers. Open-circuit voltage (Voc) of the CH3NH3PbI3 perovskite solar cell was predominantly influenced by the seed layers, where highest Voc was obtained from the ZnO nanorod grown on the colloidal seed layer. Impedance spectroscopic study revealed that recombination resistances at the seed layer contact and the ZnO nanorod/perovskite interface were increased by the colloidal coating, which was responsible for the enhanced Voc. Surface modification of ZnO nanorods improved further Voc and fill factor, leading to power conversion efficiency of 14.35%. This work emphasizes that the seed layer in the ZnO nanorod-based perovskite solar cell play major role in determining photovoltage and the ZnO nanorod/perovskite interface get involved partly in this role.

Research paper thumbnail of 11% Efficient Perovskite Solar Cell Based on ZnO Nanorods: An Effective Charge Collection System

The Journal of Physical Chemistry C, 2014

A perovskite solar cell based on ZnO nanorods was prepared, and its photovoltaic performance was ... more A perovskite solar cell based on ZnO nanorods was prepared, and its photovoltaic performance was investigated. ZnO nanorods were grown on the ZnO seed layer from solution, and their diameters and lengths were controlled by precursor concentration and growth time. CH 3 NH 3 PbI 3 perovskite infiltrated ZnO nanorods showed a power conversion efficiency of 11.13% with short-circuit current density J sc of 20.08 mA/cm 2 , open-circuit voltage V oc of 991 mV and fill factor of 0.56. Square spectral feature of external quantum efficiency (EQE) was observed, where EQE exceeded 80% in almost the entire wavelength range from 400 to 750 nm, and the integrated current density of 20.03 mA/cm 2 calculated from EQE data was in good agreement with the observed J sc. Compared to the perfect spectral response of ZnO nanorods, a perovskite solar cell based on TiO 2 nanorods exhibited an integrated current density (16 mA/cm 2) much lower than the measured J sc (20.9 mA/cm 2). In addition, time-limited photocurrent response under 530 and 700 nm monochromatic beams at 10 Hz showed that device signal amplitude, associated with charge collection, was rapidly saturated for the ZnO nanorod-based device whereas charge collection was not fully detected for the TiO 2 nanorod-based device because of slow collection rate. The current results suggest that ZnO nanorod is an effective charge collection system in CH 3 NH 3 PbI 3 based perovskite solar cells.

Research paper thumbnail of Hierarchical SnO 2 Nanoparticle-ZnO Nanorod Photoanode for Improving Transport and Life Time of Photoinjected Electrons in Dye-Sensitized Solar Cell

ACS Applied Materials & Interfaces, 2013

A hierarchical photoanode comprising a SnO(2) nanoparticle underlayer and a ZnO nanorod overlayer... more A hierarchical photoanode comprising a SnO(2) nanoparticle underlayer and a ZnO nanorod overlayer was prepared and its photovoltaic performance was compared to photoanodes consisting of SnO(2) nanoparticle only and ZnO nanorod only. The photoanode layer thickness was adjusted to about 7.6 μm to eliminate thickness effect. Ruthenium complex, coded N719, was used as a sensitizer. The photoanode composed of ZnO nanorod only showed a power conversion efficiency (PCE) as low as 0.54% with a short-circuit photocurrent density (J(SC)) of 2.04 mA/cm(2) and an open-circuit voltage (V(OC)) of 500 mV. The photoanode with SnO(2) nanoparticle only exhibited higher PCE (1.24%) because of higher J(SC) (6.64 mA/cm(2)), whereas V(OC) (340 mV) was lower than ZnO nanorod. Compared to SnO(2) nanoparticle and ZnO nanorod films, the bilayer structured film demonstrated much higher PCE (2.62%) because of both higher J(SC) (7.35 mA/cm(2)) and V(OC) (660 mV). Introduction of ZnO nanorod on the SnO(2) nanoparticle layer improved significantly electron transport and lifetime compared to the SnO(2) only film. One Order of magnitude slower charge recombination rate for the bilayer film than for the SnO(2) film was mainly responsible for the improved efficiency.

Research paper thumbnail of Quantum-Dot-Sensitized Solar Cell with Unprecedentedly High Photocurrent

Scientific Reports, 2013

The reported photocurrent density (J SC) of PbS quantum dot (QD)-sensitized solar cell was less t... more The reported photocurrent density (J SC) of PbS quantum dot (QD)-sensitized solar cell was less than 19 mA/ cm 2 despite the capability to generate 38 mA/cm 2 , which results from inefficient electron injection and fast charge recombination. Here, we report on a PbS:Hg QD-sensitized solar cell with an unprecedentedly high J SC of 30 mA/cm 2. By Hg 21 doping into PbS, J SC is almost doubled with improved stability. Femtosecond transient study confirms that the improved J SC is due to enhanced electron injection and suppressed charge recombination. EXAFS reveals that Pb-S bond is reinforced and structural disorder is reduced by interstitially incorporated Hg 21 , which is responsible for the enhanced electron injection, suppressed recombination and stability. Thanks to the extremely high J SC , power conversion efficiency of 5.6% is demonstrated at one sun illumination. Q uantum dot (QD, semiconductor nanocrystal) has been recently drawing great attention as a material for solar energy conversion due to high absorption coefficient, tunable band gap and multiple exciton generation (MEG) effect 1-4. QDs have been actively studied in dye-sensitized solar cell (DSSC) as alternatives to conventional organic dyes 5. As a result, remarkable accomplishments have been achieved in recent year, where a power conversion efficiency (PCE) of ca. 5% was achieved using metal chalcogenides 6,7 and around 10% using organic-inorganic perovskite 8. However, most of the studied QDs for DSSC were based on the relatively large band gap materials (.1.5 eV) 6-8. Using these materials, it may not be possible to utilize the full solar spectrum, which leads to a limited short-circuit photocurrent density (J SC) of ca. 20 mA/cm 2 (considering 20% loss from FTO glass) 9. No successful examples have been reported on high J SC QD-sensitized solar cells based on low band gap QDs (,1.5 eV) although it has ability to generate extremely high J SC owing to near IR absorption. Among the various low band gap QDs, PbS is one of the most intensively studied low band gap semiconductors since it has a high absorption coefficient of 1,5310 5 cm 21 and wide range of tunable band gap owing to its large bohr exciton radius of 18 nm 10,11. There have been a lot of efforts to use the PbS QD as a sensitizer. Antonio Braga et al. demonstrated a PCE of 2.21% with J SC of 10.91 mA/cm 2 using PbS/CdS QD photoelectrode being in contact with polysulfide electrolyte 12. Very recently, it was enhanced to 3.82% with J SC of 18.84 mA/cm 2 by incorporating PbS/CdS QD in hierarchical porous TiO 2 13. However, the observed J SC s are still far below the theoretical value of 38 mA/cm 2 (after considering 20% light reflection at FTO) when considering the band gap of ca. 1.0 eV 9. Main drawback of PbS QD in QD-sensitized solar cell has been argued to be inefficient charge separation and collection due to slow electron transfer kinetics 14. Electron injection from the conduction band of PbS QD to the conduction band of TiO 2 was measured to be a ca. 100 ns, which is five times slower than CdSe QD (20 ns from colloidal in organic solvent) 14. In addition, it was also argued that PbS QD served as critical recombination center, which means that injected electrons in conduction band of TiO 2 tends to recombine readily with positively charged PbS QD, and thereby efficient charge collection was seriously impeded 12,15. For efficient charge separation and collection from the PbS QD, injection and recombination kinetics of PbS QD must be tuned. However, little attempt has been made to date. Here, we report on a QD-sensitized solar cell with J SC approaching 30 mA/cm 2 based on PbS:Hg QDs. Deposition of PbS:Hg QD on nanostructured TiO 2 is implemented by simple wet chemical process, where the photovoltaic performance is evaluated by using polysulfide as a redox electrolyte. Noticeable conversion efficiency of 5.6% with unprecedented high J SC is demonstrated under AM 1.5G one sun illumination. Electron injection and charge recombination kinetics are studied by femtosecond transient absorption measurements.

Research paper thumbnail of A Preponderant Enhancement of Conversion Efficiency by Surface Coating of SnO₂ Nanoparticles in Organic MK-2 Dye Sensitized Solar Cell

Nanocrystalline SnO2 colloids are synthesized by hydrolysis of SnCl4·5H2O in aqueous ammonia solu... more Nanocrystalline SnO2 colloids are synthesized by hydrolysis of SnCl4·5H2O in aqueous ammonia solution. The synthesized SnO2 nanoparticles with ca. 15 nm in diameter are coated on a fluorinedoped thin oxide (FTO) conductive substrate and heated at 550C. The annealed SnO2 film is treated with aqueous TiCl4 solution, which is sensitzied with MK-2 dye (2-cyano-3-[5'''-(9-ethyl9H-carbazol-3-yl)-3',3'',3''',4-tetra-n-hexyl-[2,2',5',2'',5'',2''']-quater thiophen-5-yl]). Compared to bare SnO2 film, the conversion efficiency is significantly improved from 0.22% to 3.13% after surface treatment of SnO2 with TiCl4, which is mainly due to the large increases in both photocurrent density from 1.33 to 9.46 mA/cm and voltage from 315 to 634 mV. It is noted that little change in the amount of the adsorbed dye is detected from 1.21 for the bare SnO2 to 1.28 μmol/cm for the TiCl4treated SnO2. This indicates that the photocurrent ...

Research paper thumbnail of Scalable Fabrication of >90 cm 2 Perovskite Solar Modules with >1000 h Operational Stability Based on the Intermediate Phase Strategy

Advanced Energy Materials

Research paper thumbnail of Removal of residual compositions by powder engineering for high efficiency formamidinium-based perovskite solar cells with operation lifetime over 2000 h

Research paper thumbnail of A holistic approach to interface stabilization for efficient perovskite solar modules with over 2,000-hour operational stability

Research paper thumbnail of 2D Derivative Phase Induced Growth of 3D All Inorganic Perovskite Micro–Nanowire Array Based Photodetectors

Advanced Functional Materials

Research paper thumbnail of The Impact of Atmosphere on Energetics of Lead Halide Perovskites

Advanced Energy Materials

Research paper thumbnail of Inverse Growth of Large-Grain-Size and Stable Inorganic Perovskite Micronanowire Photodetectors

ACS Applied Materials & Interfaces

Research paper thumbnail of Imaging of the Atomic Structure of All-Inorganic Halide Perovskites

The Journal of Physical Chemistry Letters

Research paper thumbnail of Water splitting exceeding 17% solar-to-hydrogen conversion efficiency using solution-processed Ni base electrocatalysts and perovskite/Si tandem solar cell

ACS Applied Materials & Interfaces

Research paper thumbnail of Carbon-based Electrode Engineering Boosts the Efficiency of All Low-temperature Processed Perovskite Solar Cells

Research paper thumbnail of 1D Hexagonal HC(NH2 )2 PbI3 for Multilevel Resistive Switching Nonvolatile Memory

Advanced Electronic Materials

Research paper thumbnail of Hybrid Chemical Vapor Deposition Enables Scalable and Stable Cs-FA Mixed Cation Perovskite Solar Modules with a Designated Area of 91.8 cm2 Approaching 10% Efficiency

Journal of Materials Chemistry A

The development of scalable deposition methods for stable perovskite layer is a prerequisite for ... more The development of scalable deposition methods for stable perovskite layer is a prerequisite for the development and the future commercialization of perovskite solar modules. However, scalability and stability are the...

Research paper thumbnail of Negligible-Pb-Waste and Upscalable Perovskite Deposition Technology for High-Operational-Stability Perovskite Solar Modules

Advanced Energy Materials

Over the past few years, there have been unprecedented advances in solar cells using metal halide... more Over the past few years, there have been unprecedented advances in solar cells using metal halide perovskite materials as light absorbers. [1-3] A record power conversion efficiency An upscalable perovskite film deposition method combining raster ultrasonic spray coating and chemical vapor deposition is reported. This method overcomes the coating size limitation of the existing stationary spray, single-pass spray, and spin-coating methods. In contrast with the spin-coating method (>90% Pb waste), negligible Pb waste during PbI 2 deposition makes this method more environmentally friendly. Outstanding film uniformity across the entire area of 5 cm × 5 cm is confirmed by both large-area compatible characterization methods (electroluminescence and scattered light imaging) and local characterization methods (atomic force microscopy, scanning electron microscopy, photoluminescence mapping, UV-vis, and X-ray diffraction measurements on multiple sample locations), resulting in low solar cell performance decrease upon increasing device area. With the FAPb(I 0.85 Br 0.15) 3 (FA = formamidinium) perovskite layer deposited by this method, champion solar modules show a power conversion efficiency of 14.7% on an active area of 12.0 cm 2 and an outstanding shelf stability (only 3.6% relative power conversion efficiency decay after 3600 h aging). Under continuous operation (1 sun light illumination, maximum power point condition, dry N 2 atmosphere with <5% relative humidity, no encapsulation), the devices show high light-soaking stability corresponding to an average T 80 lifetime of 535 h on the small-area solar cells and 388 h on the solar module.

Research paper thumbnail of Lithium-ion batteries: outlook on present, future, and hybridized technologies

Journal of Materials Chemistry A

Lithium-ion batteries (LIBs) continue to draw vast attention as a promising energy storage techno... more Lithium-ion batteries (LIBs) continue to draw vast attention as a promising energy storage technology due to their high energy density, low self-discharge property, nearly zero-memory effect, high open circuit voltage,...