Shigeru Niki Director Renewable Energy Research Center(RENRC) AIST

Transcription

1 IW-CIGSTech7 June 23, 2016 Shigeru Niki Director Renewable Energy Research Center(RENRC) AIST 0

2 OUTLINE 1. Introduction 2. NEDO CIGS Consortium 3. The Terawatt Workshop 4. Summary and Future Direction 1

3 Current Status of Energy-Related Issues in Japan After the Great East Japan Earthquake in March 2011, 1. Self-sufficiency ratio in the primary energy supply dropped from ~20% in 2010 to ~6% in CO 2 emissions increased significantly (2013 was the worst ever). 3E+S Target Japanese Energy Policy for 2030 Energy Security Economic Efficiency Environment with securing Safety energy self-sufficiency: 6% 24.3%@2030 electricity cost: less than the current cost CO 2 reduction target: 26% reduction from 2013 Renewable Energy: Maximum introduction with reduced costs Energy Mix for 2030 under Long-Term Energy Supply-Demand Outlook (Agency for Natural Resources and Energy: June 2015) 2

4 Current Status of PV industries in Japan Started R&D of PV technologies at 1974 under Sunshine Project Share of Japan s module production dropped 50%@ %@2014 due to intensification of global price competition not due to the level of technologies. Over intensification of global price competition lead to stagnation and bankruptcy to many module manufactures as well as introduction of anti-dumping tariff. Japan is leading PV technologies demonstrating world record efficiencies of h=25.6% of silicon heterojunction cell (Panasonic) and h=22.3% of CIGS cell (Solar Frontier), etc. Strong domestic value chain based on various technologies Emergence of the power conditioning system (PCS) manufactures since the start of Japanese FIT in 2012 becoming the Japanese strength. 3

5 Deployment (FIT and Subsidy) Started subsidy program for residential PV system in 1994 Japanese FIT for PV started in July GW already installed, 79GW of proposals approved by METI Unbalanced geographical distribution Unbalanced deployment of PV compared to other renewables Unlimited possibilities of curtailment in some regions FIT started 4

6 Fukushima Renewable Energy Institute, AIST (FREA) 10 th regional research base of AIST Missions (based on the government s announcement, July 2011) International R&D base for renewable energy New industry promotion in the area damaged by the disaster Founded in April 2014 Experiment Building Smart System Research Facility (3MW PCS testing) Demonstration site 300kW 500kW Photovoltaics Wind Power Geothermal Hydrogen Energy Carrier Energy Network Main Building 6

7 PV technologies at AIST Renewable Energy Research Center (RENRC) and Research Center for Photovoltaics (RCPV) Hokkaido Center Kyushu Center Chugoku Center Long-term stability Oudoor testing RENRC HQ c-si technology, energy management Kansai Center FREA (from Apr. 2014) Tohoku Center Shikoku Center Chubu Center Tokyo HQ Tsukuba Center &HQ RCPV HQ CIGS, TF-Si, Perovskite, Tandem Module reliability Calibration, measurement 7

8 2. NEDO CIGS Consortium 8

9 NEDO PV Challenges New Japanese PV roadmap announced in Oct Cost target: 14 JPY/kWh in 2020, 7 JPY/kWh in 2030 Cost [JPY/kWh] Improvement in efficiencies and cost-down Application of the technologies developed in the previous projects Equivalent to commercial electricity 14 JPY/kWh Equivalent to general power sources 7 JPY/kWh System (example) Module efficiency: 22% Utilization factor: 14% Operation period: 25 years Novel materials and structures Application of novel technologies for mass-production System (example) Module efficiency: 25% Utilization factor: 15% Operation period: 30 years

10 New NEDO PV projects started ( ) Mid term h target@2017: cell 22%, submodule 19% Final h target@2019: cell 23%, submodule 20% CIGS Consortium Japan (Dr. S. Niki) Solar Frontier (Dr. T. Kato) AIST: Research Center for Photovoltaics (Dr. H. Shibata) Tokyo Tech. (Dr. A. Yamada): Ritsumeikan Univ. (Dr. T. Minemoto): Kagoshima Univ. (Dr. N. Terada) Ryukoku Univ. (Dr. T. Wada) Tsukuba Univ. (Dr. K. Akimoto) Tokyo Univ. of Sci. (Dr. M. Sugiyama)

11 CIGS Consortium Japan Acceleration of R&D by effective collaboration Tokyo Tech buffer/absorber Ritsumeikan Univ. TCO/buffer Tokyo Univ. Sci. grain boundary exchange data & samples Solar Frontier selenization sulfurization Absorbers, Devices AIST 3-stage evaporation Kagoshima Univ. band profile Ryukoko Univ. material design Tsukuba Univ. defects

12 Cost Analysis of CIGS technology Cost 23JPY/kWh 14JPY/kWh 7JPY/kWh Module price 61JPY/W 48JPY/W 31JPY/W Module efficiency 14% 16% 20% Cell efficiency 21% 23% 25% Module cost (comparative) Target schedule

13 Device Simulation Material parameter Current cells Ideal Cell carrier interface Yes No Bandgap (ev) Electron lifetime(sec) Hole lifetime(sec) Electron mobility(cm 2 /Vs) Hole mobility(cm 2 /Vs) Hole concentration(cm -3 ) Surface reflection loss 10 % 0 % Device characteristics Current cell Ideal cell efficiency(%) J SC (A/cm 2 ) V OC (V) FF

14 High-performance CIGS solar cell/submodule research Small-area Cell WR cell eff (Cd-free) 22.7 (CdS) 20.9 (Cd-free; certified) (CdS; certified) 22.0 (Cd-free; certified) cm 2 small area cell 19.0 NEDO target Cd-free Submodule (certified) SF submodule Production Module η=18.6% 40cm 2 submodule

15 Development of super high-efficiency CIGS technology device fabrication, absorber supply, junction formation, etc. Novel devices and processes for efficiencies of 23% and more AIST group TCO layer buffer layer front surface layer CIGS absorber layer back surface layer Passivation and light confinement layer Mo back electrode glass substrate Development of novel TCO materials Development of buffer layer deposition technologies Improvement of hetero-junction interface qualities Improvement of crystal qualities Improvement of crystal grain boundaries Development of back surface passivation technologies and light confinement technologies

16 Interface Engineering for High-Performace Chalcogynide Thin- Film Solar Cells Objective Cu(InGa)Se 2 thin-film solar cell consists of many interfaces, such as CdS/CIGS heterointerface, grain boundaries (GBs), and rear contacts. The efficiency of CIGS solar cells is dominated by these interfaces. In the research work, Tokyo Tech focuses on the interface engineering to improve the efficiency. Themes CdS/CIGS interface and grain boundaries (GBs) Surface treatments Band profiling and back contact engineering 2016/6/23

17 Passivation technology by band alignment control Research Object: Reduction of recombination at front junction and increase V oc & FF 1. Reduction of defect density at front junction 2. Carrier separation by band engineering New TCO and buffer layers for band alignment control Recent topic: (Cd,Zn)S/(Zn,Mg)O as more transparent buffers Eg of (Cd,Zn)S: 2.7 ev Designated area: 0.5 cm 2 (SF) EQE x=0.21 [Eg of (Zn 1-x,Mg x )O: 3.73 ev] h: 20% (J SC : 39.3 ma/cm 2 ) 0.2 x=0 [Eg of (Zn 1-x,Mg x )O: 3.3 ev] w.o. ARC Varying x=[mg]/([mg]+[zn]) 0.0 h: 18.4% (J SC : 38 ma/cm 2 ) Wavelength [nm]

18 Ryukoku University Studies on various materials, interfaces and grain boundaries in CIS solar cells by a combination of theoretical calculation and experimental methods Au /NiCr ZnO:Al (ITO) ZnO buffer layer CdS (Zn-O-S, In-S) Absorber Cu(In,Ga)(S,Se) 2 Back contact (Mo) Soda-lime glass (soda-lime glass) Materials design of interface between buffer layer and absorber layer Diffusion of various elements such as Cd or Zn atom from buffer layer into CIGS absorber layer Electric structures of various Cd-free buffer layers Materials design of CIGS absorber layer Cu(In,Ga)(S,Se) 2 absorber layer Cu(In,Ga) 3 (S,Se) 5 surface layer Defects in CIGSS crystals Grain boundaries of polycrystalline CIGSS thin films Materials design of Interface between CIGS absorber layer and Mo back contact MoSe 2 interface layer 18

19 Determination of Band Profiles throughout the Cell-Structure (I); for Developing Key Technologies for High Performance (Kagoshima Univ.) Buffer TCO Modified Reg. by PDT CIS Mo Determination of Electronic Structure by using Direct and Inverse Photoemission (in-situ PES/IPES) Mechanism of PDT Band Buffer/TCO Band Offset (CBO, VBO) at CIS/Buffer and Buffer/TCO Interfaces Optimization; Suppression of Interface-Loss CBM Built-in Potential (Sum of Interface-Induced Band Bending) through the CIS/Buffer/TCO Structure Clarification the Upper Limit of V oc VBM Band Offsets c(buffer) Originated OVC PDT Clarification of Impact of Post-Deposition-Treatment (PDT) on Electronic structure of CIS and Band Alignment at the Interface

20 Subject :Determination of Band Profiles through the Cell-Structure (II); (Kagoshima Univ.) for Developing Key Technologies for High Performance Buffer TCO Modified Reg. by PDT CIS Band Profile in CIS Mo Determination of Band Profile by using Cross Sectional UHV-Kelvin Probe Microscope (UHV-KFM) Visualization of Band Profiles in CIS (Gap-, Edge-Grading along Depth Direction) Band bending CBM Feedback to CIS-Fabrication (High Voc, J sc ) Visualization of Band Profiles at the CIS/Mo Interface PDT Band Gradient at Back Contact Enhancement of Back Surface Field VBM Band Offsets

21 University of Tsukuba Characterization of Defects in CIGS and Development of the Technique to Suppress the Defect Formation Research Results Obtained to date 1. Defect level with 0.3eV from the valence band <Admittance measurements> Result: Assigned as V Cu -V se ; Not so sensitive to device performance 2. Defect level with 0.8eV from the valence band <Photo-capacitance measurements> Result: Works as recombination center; Related to anti-site defect 3. Impurity phase in CIGS <Raman scattering spectroscopy measurements> Result: Formation of Cu 2 Se; Affects significantly device performance Research Plan 1. Detection of defect level with 0.4eV ~ 0.7eV where nobody surveyed to date Method: Photo-capacitance measurements with IR light source etc. 2. Identification of atomic structure of the 0.8eV-defect Method: Positron annihilation, Pump probe EXAFS and so on 3. Development of the technology to suppress the Cu 2 Se formation Method: Examination of deposition condition etc. 4. Identification of electronic properties at the interface, surface and grain boundary Method: EBIC, Microscopic PL and PL decay etc.

22 TUS Exploring the pathway for high efficiency CIGS solar cells by epitaxial growth technique Tokyo University of Science Task: To provide the guideline for high-efficiency CIGS solar cells by using an epitaxial growth technique leading to no grain-boundaries and less defects. Poly-CIGS solar cell Cell structure ZnO-based TCO Issues High mobility-tco Epi-CIGS solar cell Benefits Cell structure ZnO-based TCO Issues High mobility-tco Poly-Buffer Bulk defect Interface defects Low-bulk defect Low-interface defect Epi-Buffer Band offset Epitaxial growth Epitaxial growth Poly-CIGS Grain boundary Lattice defects No GB Low defects Epi-CIGS Low defects Carrier control Impurity doping Band profile Poly-Mo SLG Interface defects Diffusion from substrate (Na,K,Ca,Mg, etc.) Low defects No diffusion from substrate Epi-Mo Single crystal Buffer layer Epitaxial growth Surface cleaning

23 3. The Terawatt Workshop Global Alliance of Solar Energy Research Institutes (GA-SERI) March th, 2016 Freiburg, Germany Worldwide gathering of 50 experts from Germany, Japan, the United States and elsewhere to discuss the future of PV. Representatives from research institutes, industry and funding and financial organizations met in Kaufhaus in Freiburg, Germany Discussions centered on the challenges that must be overcome to transform the energy system and enable PV to supply a significant portion of the world s energy. 23

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25 The Terawatt Workshop (3) Statement (extracts) Global gathering addresses PV role in energy prosperity and climate change mitigation and announces transition to a new stage that will carry PV to the terawatt range With annual global PV installations reaching 60 GW in 2015, approaching global production capacity In view of drastically reduced PV costs, cumulative global installations in excess of 3 TW are anticipated by 2030, continuing current R&D and investment paths. To provide a major contribution to global climate goals, total installations on the order of 20 TW will be needed by This will require continued investment in worldwide R&D to reduce production costs, increase efficiency and improve reliability. An increasingly flexible electricity grid, increased availability of low-cost energy storage and demand side management will also play key roles in enabling accelerated PV deployment. In addition to providing a significant fraction of world electricity, PV has the potential to provide low cost energy for mobility and heating market demands. Fh. G. ISE (Germany), AIST (Japan), and NREL(USA) are the member institutes of GA-SERI. GA-SERI was founded in Press release from AIST, Fh.G and NREL on March 30,

26 4. Summary and Future Direction 1. CIGS technology climbed to the next level. 2. Over 20%-efficiency commercial modules can be expected in the near future. 3. Further improvement of small-area cell efficiency is wanted to show the potential of the CIGS technology. 4. Breakdown of high-efficiency potential to the production is critical to compete with other technologies. (Is this the roll of industry only? or can the research institutes help?) 5. Reliability issues have become more important. The allying of CIGS community is important for standardization. (for example, IEC61215) 5DO 10.3 Sakurai et. al., We need more companies to make sustainable CIGS industry. CIGS technology is one of the core PV technologies which is sustainable in the future. (competitive in terms of performance as well as cost with respect to current Si and CdTe technologies.

27 Acknowledgments AIST Research Center for Photovoltaics (RCPV): S. Ishizuka, H.Tampo, T. Koida, Y. Kamikawa, J. Nishinaga, S. H. Choi, K. M. Kim, S. H. Kim, H. Shibata, A. Yamada, H. Mizuno, R. Ohshima, K. Makita, T. Sugaya, K. Hara, A. Masuda, K. Matsubara CIGS Consortium: Solar Frontier, Tokyo Tech, Ritsumeikan Univ. Kagoshima Univ. Ryukoku Univ. Tsukuba Univ. Tokyo Univ. Sci. This work is supported, in part, by New Energy and Industrial Technology Development Organization (NEDO).

28 Thank you for your attention. あらたうと 青葉若葉の 日の光 芭蕉 2016/6/23 Copyright National Institute of Advanced Industrial Science and Technology (AIST). All rights reserved. 28

29 Appendices 2016/6/23 Copyright National Institute of Advanced Industrial Science and Technology (AIST). All rights reserved. 29

30 How to improve the energy self-sufficiency ratio in the primary energy supply? Trend in energy self-sufficiency FY2010:19.9%, FY2011:11.2%, FY2012:6.3%, FY2013:6.0% Goals set to be 24.3% at FY2030 Renewable Energy:13-14%, Nuclear:11-10% Fundamental plan of action Maximum cutdown of energy usage Maximum introduction of renewable energies Improve in efficiency for thermal power plant 一次エネルギー供給 489 百万 kl 程度 再エネ 13~14% 原子力 11~10% 天然ガス 18% 程度 Renewable (13-14%) Nuclear (11-10%) LNG:18% Reduce the dependence on Nuclear RE:maximum introduction with suppressed cost 石炭 25% 程度 LPG3% 程度 石油 30% 程度 2030 年度 Energy Mix for 2030 under Long-Term Energy Supply-Demand Outlook (Agency for Natural Resources and Energy: June 2015) Copyright National Institute of Advanced Industrial Science and Technology (AIST). All rights reserved. Coal:25% LPG:3% Oil:30% FY

31 Energy Mix (Electricity Outlook) ー maximum introduction with suppressed costs ー Role of RE will be expanded. RE: 10.7%(2013) out of total electricity 22-24%(2030) RE except for hydro power: from 2.2% (2013) to 13-15%(2030 Renewable Hydro Nuclear LNG 再エネ ( 水力以外 ) 1.1% その他ガス 0.9% LNG 29.3% 電源構成 再エネ ( 水力以外 ) 2.2% 水力 8.5% 水力 8.5% その他ガス 1.2% 28.6% 原子力 1.0% LNG 43.2% ( 総発電電力量 ) 10,650 億 kwh 程度 再エネ ( 水力以外 ) 13-15% 程度 水力 % 程度 原子力 22-20% 程度 LNG 27% 程度 地熱 % 程度 バイオマス % 程度 風力 1.7% 程度 太陽光 7.0% 程度 Geothermal ( %) Biomass ( %) Wind(~1.7%) PV (~7%) Coal Oil 石炭 30.3% 石炭 25.0% 石油 LPG 石油 LPG 石炭 26% 程度 6.6% 13.7% 石油 3% 程度 2010 年度 2013 年度 2030 年度 石油石炭 LNG その他ガス原子力水力再エネ 太陽光風力バイオマス地熱 RE introduction targe (incl. hydro) 22-24% (2030) Energy Mix for 2030 under Long-Term Energy Supply-Demand Outlook (Agency for Natural Resources and Energy: June 2015) Copyright National Institute of Advanced Industrial Science and Technology (AIST). All rights reserved. 31

32 Storage Technology -Various Storage Technologies- The integration of large shares of various renewable energy into the energy system will go hand-in-hand with the need to increase the operational flexibility of power system. Electricity storage systems can be classified by size according to their input and output power capacity and their discharge duration (hours). Hydrogen-based technologies are best suited to large-scale electricity storage applications at the megawatt scale, covering hourly to seasonal storage. 32

33 Storage Technology - Hydrogen energy carrier- hydrogen carriers :materials that enable chemical energy storage through reversible hydrogenation large scale storage at a high density (MCH(methylcyclohexane:6wt%-H 2 ) NH 3 (ammonia:17wt%-h 2 ), etc.) Cost analysis: transportation of imported renewable energy by hydrogen carriers (Liq. H 2 and MCH) Dr. Ishimoto indicated that In this paper,...the re-electrification cost in Japan is reduced to the range of the present electricity price in Japan. 33