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Nakorn Henjongchom,Nopporn Rujisamphan,Pisist Kumnorkaew,I-Ming Tang,Vittaya Amornkitbumrung,Thidarat Supasai 한국물리학회 2019 Current Applied Physics Vol.19 No.12
Methylammonium lead iodide (CH3NH3PbI3) based perovskite having low degrees of the disorder is of great interest for optoelectronic and photovoltaic applications. In this work, a layer of CH3NH3PbI3 was successfully prepared using an ultrasonically sprayed-nebulous method. Changes in structural and optical properties alongside with photo-induced charge separation and transportation behavior were systematically studied. The surface photovoltage spectra reveal a significant reduction of the density of deep defect states as the organic content was increased. It was observed that the measured values of Urbach energies decrease from 33.36 to 28.24 meV as the amount of organic content was increased to an optimum value. The best perovskite solar cells obtained using the sprayed-on approach exhibited a Jsc of 16.54 mA/cm2, a Voc of 0.99 V, and a FF of 62.4, resulting in an overall PCE of 10.09%.
Enhanced Specific Capacitance of an Electrophoretic Deposited MnO2-Carbon Nanotube Supercapacitor
Patin Tagsin,Pawinee Klangtakai,Viyada Harnchana,Vittaya Amornkitbamrung,Samuk Pimanpang,Pisist Kumnorkaew 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.12
MnO2 and MnO2-carbon nanotubes (CNT) composite films were grown directly on stainless- steel substrates using an electrophoretic process employing supercapacitor electrodes. An electrophoretic MnO2 film with a nanoplate-like structure was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Supercapacitor performance was studied using cyclic voltammetry (CV), charge-discharge (CD) and electrochemical impedance spectroscopy (EIS). The specific capacitance (SC) of the electrophoretic MnO2 film was 60 F/g at 1 A/g, with a 38.33% retention of the initial SC values after 1000 cycles. The low SC value of the MnO2 films was attributed to the high series and charge-transfer resistances of 1.70 and 3.20, respectively. The MnO2-CNT composites with the addition of 0.04, 0.06 and 0.08 g CNT to the electrophoretic MnO2 film were found to greatly increase the SC to 300, 206 and 169 F/g at 1 A/g, respectively. The series and charge-transferred resistances of MnO2-CNT composite films decreased to 1.38 - 1.52 and 2.62 - 2.86 , respectively. The SC improvement of the composite electrodes was attributed to presence of two active storage materials (MnO2 and CNT), a high film specific surface area and electrical conductivity.
Aunping Namfon,Kumlangwan Pantiwa,Towannang Madsakorn,Chanlek Narong,Kumnorkaew Pisist,Klangtakai Pawinee,Srepusharawoot Pornjuk,Thongnum Anusit,Chompoosor Apiwat,Jarernboon Wirat,Pimanpang Samuk,Rutt 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.8
CH3NH3PbI3 (MAPbI3) flm was prepared by a convective method, and its X-ray difraction spectrum displays the tetragonal perovskite structure. GeI2 and GeBr2 powders dissolve poorly in a mixed dimethylformamide-dimethylsulfoxide (DMFDMSO) solvent, but the introduction of 5 wt% 5-ammonium valeric acid iodide (5-AVAI) into the mixed DMF-DMSO solvent greatly promotes GeI2 and GeBr2 solubility. XRD spectra of the (5-AVAI)MAPbI3, MAGexPb1–xI3, and MAGexPb1–xBr2xI3–2x (x=0.0625 and 0.125) flms exhibit a tetragonal perovskite structure, but the flm morphologies become rougher than that of the pristine MAPbI3 flm. Discontinuous islands are formed on MAGexPb1–xI3 and MAGexPb1–xBr2xI3–2x (x=0.125) flms. X-ray photoemission spectroscopy (XPS) analysis detected the Ge element on all Ge-doped flms. The best performance levels of the carbon-based hole transport layer-free MAGexPb1–xI3–x (x=0.0625, η=3.63%) and MAGexPb1–xBr2xI3–2x (x=0.0625, η=2.95%) perovskite solar cells are lower than that of the pristine MAPbI3–based perovskite solar cell (η=5.28%). This is likely due to the increased surface roughness, pin-holes, isolated islands, and the decreased light absorbance of the Ge-doped flms in comparison with the pristine MAPbI3 flm.
Sutthipoj Sutthana,Kritsada Hongsith,Pipat Ruankham,Duangmanee Wongratanaphisan,Atcharawon Gardchareon,Surachet Phadungdhitidhada,Dheerawan Boonyawan,Pisist Kumnorkaew,Adisorn Tuantranont,Supab Choopu 한국물리학회 2017 Current Applied Physics Vol.17 No.4
An interfacial modification of CH3NH3PbI3/PCBM is investigated by pre-heating PCBM solution before spin-coating on the CH3NH3PbI3layer.By adjusting PCBM concentration, PCBM films were optimized to form homogeneous films. Besides, the pre-heat treatment of PCBM solution exhibits a better covered area over CH3NH3PbI3 layer with reduced pinhole compared with the non-heat treatment. This can be explained by the higher thermal energy PCBM molecules of the pre-heat solution leading to higher molecule mobility that can reorganizes a structural as well as enhance the diffusion and enhance coverage of PCBM films over CH3NH3PbI3. The optimized cell is enhanced with average power conversion efficiency from 4.59% up to 5.76% (6.44% maximum) by heat treatment. To investigate interface between CH3NH3PbI3 and PCBM, the contact angle was measured and found that the contact angle of PCBM films were higher after heat treatment suggesting re-alignment and better orientation of PCBM on perovskite film. The better orientation of PCBM can be explained in term of hydrophilic/hydrophobic property of the interface between CH3NH3PbI3 and PCBM. These results suggest that pre-heat treatment of PCBM solution has ability to modify the interface for better orientation of PCBM and resulting in efficiency enhancement due to better carrier transport direction at the CH3NH3PbI3/PCBM interfaces for perovskite solar cells. In addition, the better orientation that the head (non-polar)is oriented at outer surface can also prevent the solar cells from surrounding moisture.
Kumlangwan Pantiwa,Suksangrat Pitphichaya,Towannang Madsakorn,Faibut Narit,Harnchana Viyada,Srepusharawoot Pornjuk,Chompoosor Apiwat,Kumnorkaew Pisist,Jarernboon Wirat,Pimanpang Samuk,Amornkitbamrung 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.12
CH3NH3Pb(SCN)xI3-x films were prepared using a hot-casting method with five different Pb(SCN)2/PbI2 levels (x = 0, 0.25, 0.5, 1 and 2). Substitution of SCN- in the CH3NH3PbI3 structures induces a film color transformation from black to yellow. UV vis spectra of CH3NH3Pb(SCN)xI3-x films display an increased band gap from 1.59 eV (pure CH3NH3PbI3 film) to 2.37 eV (MAPb(SCN)2I films). Experimental XRD spectra of CH3NH3Pb(SCN)xI3-x films for increasing SCN- levels show a reduced angle of the (110) plane in the same trend as for the simulated tetragonal CH3NH3Pb(SCN)xI3-x structures. The calculated bandgap of simulated tetragonal CH3NH3Pb(SCN)xI3-x structures also increases with the SCN- concentration. Maximal efficiency, 4.56%, was gained from a carbon-based hole-transport layer (HTL)-free CH3NH3PbI3 (x = 0) perovskite solar cell. This is attributed to the low bandgap of CH3NH3PbI3 (1.59 eV). Although, the efficiency of the carbon-based HTL-free CH3NH3Pb(SCN)xI3-x solar cells decreases with increasing SCN- ratio, the excellent solar cell stability was obtained from carbon-based HTL-free CH3NH3Pb(SCN)xI3-x (x = 0.25, 0.5, 1 and 2) solar cells. This should be influenced by the presence of the hydrogen bonds between H and S and/or H and N in the CH3NH3Pb(SCN)xI3-x structures. The carbon-based HTL-free CH3NH3Pb(SCN)0.5I2.5 solar cell delivers a promising efficiency of 3.07%, and its efficiency increases by 11.40% of its initial value after 30-day storage.