Organic emiconductor and Organic olar Cells (ext generation solar cells using nanomaterials) Yutaka Matsuo Hefei ational Laboratory for Physical ciences at the Microscale University of cience and Technology of China Department of Mechanical Engineering, chool od Engineering The University of Tokyo 2016.10.11
General Overview of olar Cells
olar Energy wind power potential energy of water wave power photosynthesis solar power solar thermal chemical energy natural gas 63 years petroleum 41 years coal 147 years reverse-production ratio
History: olar Cells 1839 Becquerel, recognition of photovoltaic effect 1884 Fritts, the first solar cell (selenium/gold) 1954 AT&T Bell Lab., single crystal silicon solar cells 1991~ intensive research of dye-sensitized solar cells 2000~ intensive research of organic thin-film solar cells World market of solar cells: 2007, $12,008,000,000 (1 兆 2008 億円 ) 2012, $46,700,000,000 (4 兆 6700 億円 ) (expected) annual production [MW/year] Annual production of solar cells 2006, 2.5 GW/year 2007, 3.5 GW/year 2008, 6.9 GW/year cf. nuclear power generation: 1GW/plant year
Renewable Energy 40000 Global electricity supply [TWh] 35000 30000 25000 20000 15000 10000 5000 19% 22% 34% 55% 82% 25% conventional Marine Geothermal olar Thermal PV Wind Biomass mall Hydro Large Hydro 0 2001 2010 2020 2030 2040 Year ource: European Renewable Energy Council
CO 2 Emission: Low CO 2 Emission of olar Cells solar cells: 25 80 g-co 2 /kwh fossil fuels: 600 700 g-co 2 /kwh Global Warming:
Energy and Money Balance Energy Payback Time (EPT): E input EPT = = E producing energy used in solar cell production annual energy production (/ year) polycrystalline silicon solar cell: 1.5 (year) amorphous silicon solar cell: 1.1 (year) CI solar cell: 0.9 (year) (wind power: 0.3 year) Money Payback Time (MPT): MPT = M input M producing
Power Cost ( 発電コスト ): Cost of olar Cells Cost for Manufacturing ( 製造コスト ) Installation Operation Decommissioning i solar cell: 45 65 yen / kwh Oil-thermal power: ca. 10 yen / kwh Wind power: 10 14 yen / kwh (cf.) electricity price at home: 15 30 yen / kwh Production and purification of i: ( コークス ) C Cl 2 io 2 crude i icl 4 pure i (iemens method)
Inorganic silicon solar cells Various olar Cells compound semiconductor solar cells CIG (CI) solar cells C: copper I: indium G: gallium : diselenide (selenium) Organic organic photovoltaic cells dye-sensitized solar cells Konarka Technologies potential low-cost, lightweight, flexible, wide area
Highest Power Conversion Efficiency InGaAs-based three-layer solar cells:37.5% シャープ,2012 年 12 月 5 日発表
Highest Power Conversion Efficiency シャープ,2012 年 12 月 5 日発表
Concentrator Cells harp, PCE = 43.5%
Dye-sensitized olar Cells light electron dyes TiO 2 PCE 10% -3: Ru(dcbpy) 2 (C) 2 Grätzel, et al. ature 1991, 353, 737.
Organic Thin-film olar Cells acceptor ime 2 Ph ime 2 Ph Al PEDOT:P ITO glass H H donor Potential low-cost, large area, light weight, flexible substrate
History of Organic emiconductors
emiconductors log σ insulator 絶縁体 σ:conductance ( 電気伝導度, 導電率 )[ m -1 ] (Ω -1 m -1 ) semiconductor 半導体 conductor 導体 20 15 10 5 0 5 polystyrene diamond glass AgBr silicon germanium iron copper ordinary organic compounds Characteristics of semiconductor variable conductance controlled with outer electric field: transistors two charges (electron, hole) for two carriers (n-type, p-type): diodes
The First Organic emiconductors + Br 2 perylene 赤松秀雄井口洋夫松永義夫 ature 1954, 173, 168.
Perylene:Bromine Complexes perylene 1:2 :bromine 1:3 1:4 resistivity ( 電気抵抗率 ) conductivity 電気伝導度 ( 導電率 ) 20 [Ω cm] 1 = resistivity 20
Organic emiconducting Materials Organic compounds having semiconducting property (charge can be transported in organic materials => organic semiconductors) p-type organic semiconductors (electron donors): hole transporting H H n Acenes phthalocyanine polythiophene rubrene triarylamines n-type organic semiconductors (electron acceptors): electron transporting H O O O O H F F F F F F F F F F F F F F O O Me perylene diimide perfluoro acenes fullerene fullerene derivatives
Features of Organic emiconductor Devices Potential low-cost Lightweight Flexible Wide area devices Low-temperature, low-energy processes Molecular Design Electronic, photo-electronic, and thermal properties Processes olution process (wet process) Printing technology
History of Organic emiconducting Devices Organic emiconducting Materials (1954 ) charge transfer complexes (1973~) OLED(single crystal) (1962~) OFET (1984~) OLED(layered) (1987~) Organic Photoconductors (1970 ) OPV(chottky)(1970~) OPV(p-n junction) (1986~) OPV(bulk heterojunction) (1995~) OLED displays (1997~) DC (1991~) Organic Electronics
AgX vacuum level hn ilver Halide Photography Ag + 1/2 X 2 exposure time: ca. 8 hours conduction band trap electron injection hn 1 lower bandgap (600 nm) The first photograph by iepce (1826) valence band AgX Organic Dye 0 AgX+ dye AgX dye-sensitizing: H. W. Vogel (1873) I + 600 500 400 wavelength (nm) [ 亀山直人 福本務 工化, 42, 489 (1939)]
Organic Photoconductors (OPC) Laser printer, Copy machine: [1] [2] O Ti OPC [3] TiOPc photo photo [4] 1. Electric charge 2. Exposure, Charge recombination 3. etting toner on the charged parts 4. Transcription, Printing x charge transport layer charge recombination x OPC Al substrate
From Organic emiconductors toward Organic Electronics Devices organic solar cells organic light emitting diodes organic transistors
Organic Field Effect Transistor Hole Transport Electron Transport ource hole Drain ource electron Drain + + + + + + + + + + + + + + + + + + + + + Gate (negative applied voltage) Gate (positive applied voltage)
The First Organic FET n 2,2'-bithiophene 10 μm electrochemical polymerization polythiphene Au io 2 i (n-doped) channel current, I D (na) gate voltage, V G D io 2 In-Ga drain voltage, V D (V) G 肥塚裕至 有機 FET のルーツは日本にあった!: 導電性ポリマーから超伝導まで 化学 2001 年 10 月号 A. Tsumura, H. Koezuka, T. Ando, Appl. Phys. Lett. 1986, 49, 1210.
OLED (Monolayer, Thin-Film) Anthracene Thin-Film Al Au glass cathode light emitting layer (0.4 0.6 µm) anode Vacuum Deposition Au substrate operation voltage: 30 V external quantum efficiency:0.03% anthracene source + + Al + + + + + Au hole injection: good electron injection: bad Vacuum chamber P.. Vincett et al., Thin olid Film 1982, 94, 171.
OLED (Bilayer) Mg:Ag Emission Layer (EML) + + + + + + 60 nm Me O O Al O Me Alq 3 Hole-Transporting Layer (HTL) 75 nm + ITO good hole and electron injection balance green emission of Alq 3 (540 nm) emission starting from 3 V operation voltage 8 V, current density 100 ma/cm 2, luminance 1000 cd/m 2 external quantum efficiency 1% Organic Electroluminescent Diodes C. W. Tang and. A. Van lyke, Appl. Phys. Lett. 1987, 51, 913. Me Me TAPC
Organic olar Cells Al electrode buffer layer Organic Electron Donors: Organic Electron Acceptors: O Acceptor Donor Cu O PTCBI buffer layer CuPc ITO electrode glass substrate n polythiophene C 60 C. W. Tang, Appl. Phys. Lett. 1986, 48, 183; U.. Patent (1979).
Physical Properties of Organic emiconducting Materials
Molecular Orbital vs. olid tate Physics olid tate Physics conduction band ( 伝導帯 ) band gap (Eg) forbidden band ( 禁制帯 ) conductor 導体 semiconductor 半導体 insulator 絶縁体 valence band ( 荷電子帯 ) Organic p-electron conjugated molecules ( 最低空軌道 ) ( 最高被占軌道 ) LUMO HOMO HOMO-LUMO gap molecular orbital
Properties of Organic emiconductor Carrier Mobility Ionization Potential (HOMO Levels) Electron Affinity (LUMO Levels) Light Absorption Light Emission OFET, OLED, OPV OFET, OLED, OPV OFET, OLED, OPV OPV OLED
Carrier Mobility, Carrier Density Depending on ample ize 試料サイズによる Voltage [V], 電圧 Resistance [Ω] = 電気抵抗 Current [A], 電流 large area short length = small resistance Independent of ample ize, Inherent Parameter for Materials 試料サイズによらない, 物質固有のパラメータ Resistivity(ρ) [Ω m] = 抵抗率 Resistance [Ω], 電気抵抗 Length [m], 長さ x Area [m 2 ] 面積 Conductivity 伝導率 (σ): inverse of Resistivity ( 導体, 半導体, 絶縁体を区別 ) Conductivity(σ)[Ω -1 m-1 ] 伝導率 ( [/m] ) = 1 Resistivity(ρ) [Ω m] 抵抗率
Carrier Mobility, Carrier Density Conductivity(σ)is proportional to charge of carrier, carrier density(n), and carrier mobility (μ) キャリアのもつ電荷 電荷密度 電荷移動度 (= 電気素量 ) Conductivity(σ) [Ω -1 m -1 ] = elementary charge [C] x carrier density(n) [m -3 ] x carrier mobility(μ) 電気素量 dimension of mobility: [Ω-1 m -1 ] [C] [m -3 ] = [A V-1 m -1 ] [A s] [m -3 ] = [m 2 /Vs] Carrier Density(n):valuable for each devices (c.f., doping) Carrier Mobility(μ): fundamental value for each materials
Carrier Mobility Mobility (cm 2 /Vs) at room temperature Inorganic emiconductors Organic emiconductors GaAs (single crystal, electron) 7500 rubrene (single crystal, hole) 40 GaAs (single crystal, hole) 400 pentacene (film, hole) 1.5 i (single crystal, electron) 1500 C 60 (film, electron) 1.4 i (single crystal, hole) 450 semiconducting polymers (hole) 0.1 i (polycrystalline, electron) 500 i (amorphous, hole) 1 ITO (hole) 100 n gallium arsenide
mobility Mobility
Mobility Balance 10-3 CLC mobility [cm 2 /Vsec] 10-4 10-5 hole mobility balance H H electron Me i i 10-6 P3HT CuPc BP PCBM PCBB PFL IMEF donor acceptor
(High Mobility Materials)
Materials for OFET R R n n = 2 3 R = H, C 6 H 13 uzuki 0.18 cm 2 /Vs H H R Bao C 8 H 17 C 8 H 17 himizu 0.1 cm 2 /Vs R R = Br, C, CF 3 Bao 0.3 cm 2 /Vs R R H H n n = 4 8 R R = H, C 6 H 13 himizu 0.5 cm 2 /Vs C 6 H 13 R R = Me, n-pr, silylalkynyl Kobayashi, Takahashi, Anthony himizu 1.3 cm 2 /Vs C 6 H 13
Materials for OFET Katz 0.04 cm 2 /Vs Zhu 0.045 cm 2 /Vs Takimiya 2.9 cm 2 /Vs Ar Katz 0.05 cm 2 /Vs Yamaguchi 0.51 cm 2 /Vs Ar Takimiya 0.1 cm 2 /Vs Katz 0.15 cm 2 /Vs Takimiya 10-3 cm 2 /Vs R Katz R Takimiya 0.2 cm 2 /Vs R Bao, Valiyev 0.1 cm 2 /Vs Takimiya 0.3 cm 2 /Vs 0.8 cm 2 /Vs
Polymer Materials for OFET C 6 H 13 n P3HT 0.1 cm 2 /Vs cience 1998, 280, 1741. C 12 H 25 0.18 cm 2 C 12 H 25 /Vs APL 2005, 86, 142102. n C 15 H 31 C 15 H 31 0.25 cm 2 /Vs Adv. Mater. 2006, 18, 3029. C 6 H 13 C 6 H 13 チエノチオフェン C 16 H 33 C 16 H 33 ベンゾチアジアゾ ル n C 10 H 21 C 10 H 21 シクロペンタジチオフェン 0.15 cm 2 /Vs 0.17 cm 2 /Vs n JAC 2005, 127, 1078. JAC 2007, 129, 3472. C 14 H 29 C 6 H 13 C 6 H 13 n n C 6 H 13 C 6 H 13 C 14 H 0.15 cm 2 /Vs 29 0.25 cm 2 /Vs at. Mater. 2006, 5, 328. JAC 2007, 129, 4112. i 0.06 cm 2 /Vs JAC 2006, 128, 9035. n ジチエノシロール n C 12 H 25 チアゾロチアゾール C 12 H 25 C 12 H 25 C 12 H 25 0.14 cm 2 /Vs Adv. Mater. 2007, 19, 4160. 0.27 cm 2 /Vs. Tokito C 16 H 33 C 16 H 33 n C 16 H 33 0.06 cm 2 /Vs. Tokito C 16 H 33 n n
Evaluation of Carrier Mobility (1) TOF (Time-of-Flight) method electrode pulse irradiation electrode 光励起されたキャリアの膜厚方向の移動度を測定 パルス照射 ( 窒素レーザ光,400ps) 過渡電流波形を測定, ドリフトタイムがわかる. organic thin-film oscilloscope mobility(μ)[cm 2 /Vs]= drift speed per unit electric field 単位電界あたりの電荷の移動速度 ( 距離 / 時間 ) = drift length, 移動距離 (thickness, 膜厚 )L [cm] electric field, 電界強度 E (V/d) [V/cm] x drift time, ドリフトタイム t [s]
Evaluation of Carrier Mobility (2) FET (field effect transistor) plot I Dsat = (WµC/2L)x(V G V t ) 2 (slope) 2 =WµC/2L W: channel width, チャネル幅 ; L: channel length, チャネル長 C: capacitance per unit area (insulator), 絶縁膜の単位面積あたりの静電容量 I Dsat : saturated drain current, 飽和ドレイン電流 V G : gate voltage, ゲート電圧 ; V t : threshold voltage, しきい値電圧 µ: mobility, 移動度
Evaluation of Carrier Mobility (3) CLC model (pace Charge Limited Current, 空間電荷制限電流 ) electron Aluminum / FL (IMEF or PCBM) / LiF / Aluminum (film thickness = 220 nm fabricated from 1.25 wt% solution) Al FL LiF/ Al J CLC =9/8 ε r ε 0 µ V 2 /L 3 10 5 10 5 10 4 10 4 1000 1000 J [ma/cm 2 ] 100 10 J [ma/cm 2 ] 100 10 1 1 0.1 Experimental J CLC 0.1 Experimental J CLC 0.01 0 0.5 1 1.5 2 2.5 3 3.5 4 0.01 0 0.5 1 1.5 2 2.5 3 3.5 4 Voltage [V] Voltage [V] IMEF: 8 10-3 [cm 2 /Vs] PCBM: 6 10-3 [cm 2 /Vs]
Evaluation of Carrier Mobility (3) CLC モデル (pace Charge Limited Current, 空間電荷制限電流 ) 9 J = e r e 0 µ 8 V 2 L 3 J: current density, 電流密度 [A/m 2 ] V: voltage, 電圧 [V] L: thickness, 膜厚 [m] e r : relative permittivity, 比誘電率 [dimensionless, 無次元量 ] e 0 : electric constant, 真空の誘電率 (8.854 10-12 [F/m] ([A m/v s])) (e r = e/e 0, e: permittivity, 誘電率 ) µ: mobility, 移動度 [m 2 /V s] P. E. Burrows, Z. hen, V. Bulovic, D. M. McCarty,. R. Forrest, J. A. Cronin,. R. Forrest, J. Appl. Phys. 1996, 79, 7991.
Evaluation of Ionization Potential (1) 光電子分析法 ( 電子計数方式, 大気中 ), photoelectron counting at normal pressure E T E T vacuum level 真空準位 LUMO IP (number of photoelectron) 1/2 threshold energy しきい値 E T energy of light irradiation (ev) HOMO 理研計器 AC-1, AC-2, AC-3
Evaluation of Ionization Potential (2) 光電子収量分光 (PY, Photoelectron Yield pectroscopy), 真空中, 大気中 in vacuo and at normal pressure spectrometer electrode photoelectron ammeter ultraviolet light ( ケースレー 6430 等 ) chamber sample 飛び出た電子を補償する電流を測定 ( 光電子計数方式よりシンプル ) サンプルにわずかに負電圧を印加し, 電子が飛び出し易いようにする 住友重工 PY-201
Evaluation of Ionization Potential (3) 紫外光電子分光 (UP, Ultraviolet Photoelectron pectroscopy), 超高真空下 真空準位 Ev HOMO work function 仕事関数 光電子の運動エネルギー E k incident energy (ultraviolet light) 紫外光の入射エネルギー hn ( 運動エネルギーゼロの光電子 ) zero kinetic energy measurement of photoelectron kinetic energy (E k ) 光電子の運動エネルギー E k を測定
Evaluation of Ionization Potential (4) Kelvin Probe Method (KPM) electrode sample reference electrode This measurement gave a Fermi level of organic semiconductors rather than ionization potential of them. Oscillation of two materials having different work function (WF) affords alternating current AC. To cancel the generated AC, offset voltage is applied. WF (Fermi level) of the sample = WF of the reference electrode offset voltage 表面科学 2002, Vol. 23, o. 7, 455.
Evaluation of Ionization Potential (5) Quantum Chemical Calculation, : electrochemical, : theoretical B3LYP/6-31g* Theoretical calculation tends to give lower (stable) energy levels. Chem. Mater. 2011, 23, 1646.
Evaluation of Electron Affinity Electrochemical tudy (Cyclic Voltammetry) E 1/2 red1 1.06 V i i E LUMO = (4.8 1.06) = 3.74 [ev] E LUMO [ev] = (E 1/2 red1 [V vs. Fc/Fc + ] + 4.8) R.. Ashraf et al., Macromol. Rapid Commun. 2006, 27, 1454. W.-Y. Wong et al., at. Mater. 2007, 6, 521. Y. Matsuo et al. J. Am. Chem. oc. 2008, 130, 15429.
Exciton, エキシトン ( 励起子 ) An electron/hole pair of the excitation state + + + Frenkel exciton ( フレンケル励起子 ) Mott-Wannier exciton ( ワニエ励起子 ) (charge transfer) ( 電荷移動型 ) organic semiconductors silicon, inorganic semiconductor closed electron and hole (~1 nm) separated electron and hole (~10 nm) OELD: charge recombination of hole and electron generates exciton. OPV: light absorption of organic molecules generates exciton.
Exciton Diffusion Length, 励起子の拡散距離 exciton diffusion light absorption exciton diffusion length, L D 励起子の拡散距離 :ca.10 nm exciton separation triplet excitation state: ca.10 30 nm electron diffusion hole diffusion P. Peumans, A. Yakimov,. R. Forrest, J. Appl. Phys. 2003, 93, 3693-3723. L D = 6.5 nm L D = 13 nm acceptor donor α-pd C 60
Exciton Diffusion Length, Doping Doping Triplet Materials PD PD +1wt% Ir(ppy) 3 L D 6.5±0.3 nm 9.4±0.5 nm PD Ir PD +5wt% Ir(ppy) 3 11.8±0.6 nm CBP Ir(ppy) 3 W. A. Luhman, R. J. Holmes, Appl. Phys. Lett. 2009, 94, 153304.
Basics of Organic olar Cells
Photovoltaic Mechanism - cathode ( ) n-type acceptor p-type donor D* A A- D* D+ A- D+ A D A- D+ anode ( ) light absorption exciton generation exciton diffusion electron transfer charge separation + charge transportation charge collection
Photovoltaic Mechanism LUMO hn hole cathode HOMO p-type donor electron transfer LUMO anode electron V OC HOMO n-type acceptor
Device Configuration of Organic olar Cells ormal structure Inverted structure hn electrode (Al) e e hole blocking layer phenanthroline electron acceptor electron donor hole transporting layer transparent conductive electrode e h + h + e PEDOT:P electrode (Au) hole transporting layer electron donor electron acceptor electron collecting layer transparent conductive electrode PEDOT:P hn TiOx, ZnO hn cf. Organic light emitting diodes electrode (Al) electron injecting layer electron acceptor e electron donor hole injecting layer transparent conductive electrode LiF, Li(quinolinolate) h + PEDOT:P cf. Dye-sensitized olar cells e Pt organic dye h + e e TiO 2 transparent conductive electrode
tructures of Active Layers Al Al Al Al organic n-type V semiconductor V V V p-type metal glass ITO glass ITO glass ITO glass acceptor donor chottky junction (Calvin cell) 1958 PCE = 0.01% pn heterojunction (Tang cell) 1986 PCE = 1% bulk heterojunction (ariciftci cell) 1995 PCE = 5% good carrier formation bad carrier transport interpenetrating nanostructure cell 2009 PCE > 7% good carrier formation good carrier transport
Fabrication of Organic olar Cells (3), (6) (1), (2) (4), (5) 1. Cleaning of ITO glass (UV/ozone cleaner) 2. pin-coating of PEDOT:P (hole transport material) in air, then baking 3. pin-coating of the active layer in glovebox, then thermal annealing 4. Vacuum deposition of the hole blocking layer 5. Vacuum deposition of the back electrode 6. Encapsulation of the device in glovebox
Fabrication of Inverted Organic olar Cells Patterned ITO ol-gel or chemical bath deposition process for making inorganic metal oxide layer pin coating of the active layer spin coater and hot plate pin coating of the PEDOT:P layer Thermal annealing Vacuum deposition of gold electrode vacuum deposition coater
Fabrication of Large-Area Organic olar Cells lamination Au PEDOT:P active layer TiOx ITO bar coater
Fabrication of Large-Area Organic olar Cells 1. pin-coating to form organic thin-films 2. cribing with cotton swab 3. Vacuum deposition of back electrode 4. Completion
Fabrication of Large-Area Organic olar Cells Miraikan Museum (Odaiba) Exhibition next to the poly(acetylene) film
Roll-to-Roll Process on Flexible Plastic ubstrate PET-ITO film ZnO nanoparticle, slot dye coating (stabilizer: methylethylacetic acid; solvent: acetone) "slot dye coating" ink Active layer, slot dye coating (P3HT:PCBM in chlorobenzene) head meniscus PEDOT:P, slot dye coating film ilver paste, screen printing device structure: Cold lamination Ag paste hole transport layer active layer ZnO Ps PET-ITO film e
Evaluation of Performance 1 3 4 2 1. olar imulator: Xenon Lump and Air Mass (AM) Filter 2. Power ource: For Xenon Lump 3. ource Meter Unit: Output=Voltage, Input=Current 4. PC: Control, Data Reduction 5. Photon Counter: For Data Calibration
Air Mass (AM) Artificial un Light
Characteristic of Organic Photovoltaic Devices V OC J C Open Circuit Voltage(V OC : 開放電圧 )[V] 太陽電池に何もつながない状態で 太陽電池の両端に発生する電圧 hort-circuit Current Density(J C : 短絡電流密度 )[ma/cm 2 ] 太陽電池の両端をショートさせた状態で ショートして流れる電流それを受光面積で割ったもの
Characteristic of Organic Photovoltaic Devices voltage at maximum power 最大出力となるときの電圧, V max V OC, 開放電圧 current at maximum power 最大出力となるときの電流, J max J C, 短絡電流密度 FF ( フィルファクタ, 曲線因子 ) = maximum power 最大出力点 [mw/cm 2 ] V max J max V OC J C ideal maximum power 理想的な最大出力 [mw/cm 2 ] PCE ( エネルギー変換効率 ) = (power conversion efficiency) V max J max (max. power [mw/cm 2 ]) x 100 = V OC J C FF incident energy(100 [mw/cm 2 ]) 入射光のエネルギー
IQE and EQE Internal Quantum efficiency (IQE), 内部量子効率 IQE = = number of electrons on external circuit, 外部回路を流れる電子数 number of absorbed photons, 吸収した光子数 exciton diffusion efficiency x charge transfer efficiency x charge collection efficiency エキシトン拡散効率 x 電荷移動効率 x 電荷捕集効率 External Quantum efficiency (EQE), 外部量子効率 EQE = = number of electrons on external circuit, 外部回路を流れる電子数 number of incident photons, 入射した光子数 light absorption efficiency of incident light at active layer x IQE 活性層における入射光の吸収効率 x IQE
Measurement of EQE Incident Photon to Current Efficiency (IPCE) at certain wavelength irradiation IPCE = number of electrons number of incident photons = J C P inc 1240 λ x100 J C : 短絡電流密度 [A/cm 2 ] λ: 波長 [nm] P inc : 入射光のパワー [W/cm 2 ] (1240 を < 光の波長 [nm] > で割ると, < 光のエネルギー [ev] >) monochromic incident light power measurement (w/ photon counter) photocurrent measurement
IPCE pectrum 50 2 40 IPCE 1.5 IPCE [%] 30 20 AM1.5G 1 10 400-700nm 700-1000nm 0.5 0 400 600 800 1000 wavelength [nm] 0