Work function and interface control of amorphous IZO electrodes by MoO3 layer grading for organic solar cells

Kim, Hyo Joong; Seo, Ki Won; Noh, Yeonhui; Na, Seok In; Sohn, Ahrum; Kim, Dong Wook; Kim, Han Ki

doi:10.1016/j.solmat.2015.05.036

Cited by 38 publications

(18 citation statements)

References 39 publications

(40 reference statements)

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“…Interfaces between MHP EML and HIL or ETL have a strong influence on the EL efficiency of PeLEDs because MHPs have different optical and electronical properties with conventional organic or inorganic interlayers. MHPs have a much deeper VBM (≈5.6 eV in MAPbI 3 , and ≈5.9 eV in MAPbBr 3 ) than the workfunction (WF) of conventional transparent conductive oxide (TCO) electrodes (≈4.8 eV in ITO, ≈5.0 eV in fluorine‐doped tin oxide (FTO), ≈5.0 eV in indium zinc oxide (IZO)) and than that of hole injection materials (≈4.8 eV in PEDOT:PSS, ≈5.3–5.4 eV in NiO x ). MHP also have a CBM (≈3.6 eV in MAPbI 3 , ≈3.6 eV in MAPbBr 3 ) that is shallower than the WF of conventional metal‐oxide electron transport materials (≈4.2 eV or ≈3.7 eV in ZnO).…”

Section: Limitations To Luminescence Efficiency Of Mhps and Ledsmentioning

confidence: 99%

Strategies to Improve Luminescence Efficiency of Metal‐Halide Perovskites and Light‐Emitting Diodes

2018

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emitters (FWHM ≈ 30 nm; color gamut ≈100% in NTSC standard and <90% in Rec. 2020 standard). [11][12][13][14][15] MHPs are composed of three atoms or molecules in simple crystal structures, ABX 3 or A 2 BX 4 , where A is an organic ammonium (OA, e.g., methylammonium (MA; CH 3 NH 3 + ) and formamidinium (FA; CH(NH 2 ) 2 + )) or an alkali metal cation (e.g., Cs + ), B is a transition metal cation (e.g., Au 2+ , Sn 2+ , Mn 2+ , and Pb 2+ ), and X is a halide anion (I − , Br − , and Cl − ). In 3D ABX 3 cubic crystal structure, one B cation is coordinated to the six halide anions in a corner of BX 6 octahedral con figuration and A is located in the octahe dral voids. Although bandgap formation mechanism of MHP crystals is still under debate, electronic structure of MHP crys tals is mainly contributed by the inor ganic BX 6 octahedra rather than by the A cations; [16][17][18] these studies indicate that emission wavelength λ of MHP emitters can easily be tuned (380 ≤ λ ≤ 1000 nm) by totally or partially replacing B cations or X anions. Perov skite crystal structure is also affected by Asite cations due to hydrogen bonding and vibrational coupling between BX 3 − and A + , so bandgap and concomitant λ of MHPs can be controlled by tuning the Asite cations. [19,20] These emission spectra with high color purity and wide λ tunability do not depend on the size of grains or crystals of MHP emitters when their dimen sion is larger than exciton Bohr diameter D B ; [21,22] this size independent high color purity of MHPs is particularly suited as a vivid natural color emitter in future display technology.Because of their unique crystal structure (e.g., ionic bonding) and bandgap formation mechanism, MHPs have balanced and high charge carrier mobility (e.g., both electron and hole mobility ≈ 1000 cm 2 (V s) −1 in CsPbBr 3 single crystals [23] ) and have comparable energy level to those of organic semiconduc tors. [24] Furthermore, MHP emitters have low material cost and good compatibility with diverse solution processes to synthe size MHP crystals; these are great advantages of MHPs to mass production and commercialization.In the early 1990s, several researchers tried to fabricate the MHP lightemitting diodes (PeLEDs) by using layered MHP emitters as an emitting layer (EML). [25,26] However, MHPs showed low photoluminescence quantum efficiency (PLQE), and yielded bright electroluminescence (EL) only at cryogenic temperature, which may be ascribed to immature MHP crystalli zation processes, ineffective confinement of electrons and holes, Metal-halide perovskites (MHPs) are well suited to be vivid natural color emitters due to their superior optical and electrical properties, such as narrow emission linewidths, easily and widely tunable emission wavelengths, low material cost, and high charge carrier mobility. Since the first development of MHP light-emitting diodes (PeLEDs) in 2014, many researchers have tried to understand the properties of MHP emitters and the limitations to luminescence efficiency (LE) of PeLEDs, and have devoted ...

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Section: Limitations To Luminescence Efficiency Of Mhps and Ledsmentioning

confidence: 99%

Strategies to Improve Luminescence Efficiency of Metal‐Halide Perovskites and Light‐Emitting Diodes

2018

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“…To fabricate c-ITO films with nano-scale surface roughness, an ITO and Ag graded sputtering technique was employed, as we described previously 33 34 . A direct current (DC) magnetron sputtering system with tilted multi-cathode guns was used for graded sputtering as illustrated in Figure S1.…”

Section: Methodsmentioning

confidence: 99%

Tin doped indium oxide anodes with artificially controlled nano-scale roughness using segregated Ag nanoparticles for organic solar cells

Kim

Noh

et al. 2016

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Nano-scale surface roughness in transparent ITO films was artificially formed by sputtering a mixed Ag and ITO layer and wet etching of segregated Ag nanoparticles from the surface of the ITO film. Effective removal of self-segregated Ag particles from the grain boundaries and surface of the crystalline ITO film led to a change in only the nano-scale surface morphology of ITO film without changes in the sheet resistance and optical transmittance. A nano-scale rough surface of the ITO film led to an increase in contact area between the hole transport layer and the ITO anode, and eventually increased the hole extraction efficiency in the organic solar cells (OSCs). The heterojunction OSCs fabricated on the ITO anode with a nano-scale surface roughness exhibited a higher power conversion efficiency of 3.320%, than that (2.938%) of OSCs made with the reference ITO/glass. The results here introduce a new method to improve the performance of OSCs by simply modifying the surface morphology of the ITO anodes.

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“…Moreover, obtaining high quality oxide film with high transparency and conductivity often requires a high temperature that is harmful to the devices [23,27]. Therefore, several alternative approaches have been explored and proposed by many scientific groups to develop a top electrode [28,29].…”

Section: Introductionmentioning

confidence: 99%

Yb:MoO3/Ag/MoO3 Multilayer Transparent Top Cathode for Top-Emitting Green Quantum Dot Light-Emitting Diodes

et al. 2020

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In this study, we report on the application of a dielectric/ultra-thin metal/dielectric (DMD) multilayer consisting of ytterbium (Yb)-doped molybdenum oxide (MoO3)/silver (Ag)/MoO3 stacked as the transparent cathode in top-emitting green quantum dot light-emitting diodes (QLED). By optimizing the Yb doping ratio, we have highly improved the electron injection ability from 0.01 to 0.35. In addition, the dielectric/ultra-thin metal/dielectric (DMD) cathode also shows a low sheet resistance of only 12.2 Ω/sq, which is superior to the resistance of the commercially-available indium tin oxide (ITO) electrode (~15 Ω/sq). The DMD multilayer exhibits a maximum transmittance of 75% and an average transmittance of 70% over the visible range of 400–700 nm. The optimized DMD-based G-QLED has a smaller current leakage at low driving voltage. The optimized DMD-based G-QLED enhances the current density than that of G-QLED with indium zinc oxide (IZO) as a cathode. The fabricated DMD-based G-QLED shows a low turn-on voltage of 2.2 V, a high current efficiency of 38 cd/A, and external quantum efficiency of 9.8. These findings support the fabricated DMD multilayer as a promising cathode for transparent top-emitting diodes.

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Work function and interface control of amorphous IZO electrodes by MoO3 layer grading for organic solar cells

Cited by 38 publications

References 39 publications

Strategies to Improve Luminescence Efficiency of Metal‐Halide Perovskites and Light‐Emitting Diodes

Strategies to Improve Luminescence Efficiency of Metal‐Halide Perovskites and Light‐Emitting Diodes

Tin doped indium oxide anodes with artificially controlled nano-scale roughness using segregated Ag nanoparticles for organic solar cells

Yb:MoO3/Ag/MoO3 Multilayer Transparent Top Cathode for Top-Emitting Green Quantum Dot Light-Emitting Diodes

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