perovskite-silicon tandem solar cells - smeits.rs lovro markovic.pdf · albrecht s, rech b. on top...
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Lichttechnisches Institut, Fakultät für Elektrotechnik und Informationstechnik, KIT
32. Međunarodni kongres o procesnoj industriji, Beograd, 30-31. maj 2019 32nd International Congress on Process Industry, Belgrade, May 30-31, 2019
Perovskite-Silicon Tandem Solar Cells
Lovro Marković, University of Zagreb
Table of Content
Solar Cells in General
Perovskites
About Tandems
Architectures
Materials Optimization
Fabrication / Modules
Perovskites braking records
https://www.photon.info/en/news/oxford-pv-achieved-273-percent-conversion-efficiency-perovskite-solar-cell
Promises of perovskite materials
Absorption and diffusion
Bandgap and high voltage
Solution processable
Lightweight
Paetzold U. Perovskites Photovoltaics - Lecture slides. Lichttechnisches Institut, KIT.
Promises of perovskite materials
https://www.solarpowerworldonline.com/2015/04/the-perfect-marriage-silicon-and-perovskite-solar-cells/
Why tandems?
Peters M et al. Spectrally-Selective Photonic Structures for PV Applications. Energies. 2010; 3(2): 171-193Liu Z. Optical loss analysis of silicon wafer based solar cells and modules. 10.13140/RG.2.2.26172.74881.
Thermalisation losses
Sub-bandgap losses
Why tandems?
https://www.quora.com/What-are-the-physical-limitations-were-hitting-in-solar-PV-efficiency-and-where-might-we-see-breakthroughs; De Vos, A. Detailed balance limit of the efficiency of tandem solar cells. Journal of Physics D: Applied Physics. 1980; 13 (5): 839-846
Surpassing Shockley–Queisser limit
Why perovskite / Si tandems?
Suitable bandgap span (1.5 – > 2.2 eV)
High transparency (<Eg) – small Urbach tail – sharp abs. edges
Solution processable (low-cost)
Si – the most mature and developed PV technology
Albrecht S, Rech B. On top of commercial photovoltaics. Nat. Energy. 2017; 2: 16196
Different architectures
two-terminal monolithic mechanically stacked four-terminal
Bush, K A et Al. 23.6%-efficient monolithic perovskite/silicon tandem solar cells with improved stability. Nat. Energy. 2017; 2 : 17009
2T structure
Tunnel junction in between
Higher possible efficiencies (less additional circuits, reduced parasitic absorption)
„Current-matching”
Grant, D T et Al. Design guidelines for perovskite/silicon 2-terminal tandem solar cells: an optical study. Opt. Express. 2016; 24: A1454-A1470
4T structure
Both sub-cells independently optimized
Independent of seasonal and angular variations in solar spectrum
Additional circuitry
Jaysankar M et Al. Four-Terminal Perovskite/Silicon Multijunction Solar Modules. Adv. Energy Mater. 2017; 7: 1602807
First Perovskite / Si tandem
Produced in 2015!
Achieved 13.7%
Problems with „current-matching”
Bandgap optimization in 2T
Tunable by changing halide concentrations
Should be in range 1.7-1.8 eV
Covering the majority of solar spectrum
„Current – matching” – higher voltage – lower current
Stability problems of possible materials
Top-cell materials
Cs0.17FA0.83Pb(Br0.17I0.83)3
Addition of Cs to improve photo- and thermal- stabilityMaintaining the high-efficiency level
Top-cell materials
Addition of Rb (smaller than Cs)
Improving efficiency and hysteresis of the top-cell
Better transparency (84%, in range 720–1100 nm)
4T world record!!!
Or?
https://www.photon.info/en/news/oxford-pv-achieved-273-percent-conversion-efficiency-perovskite-solar-cell
Bottom-cell materials
Silicon heterojunction (SHJ)
Highest efficiency silicon technology
Optimal light-management
Parasitic absorption
Achieving sub-bandgap transparency of top cell (sharp absorption edges)
Lack of appropriate ARC and textured surface on the bottom cell
Bottom Si cell ( ≈ 10% PQE)
Duong, T et Al. Rubidium multication perovskite with optimized bandgap for perovskite silicon tandem with over ‐26% efficiency. Adv. Energy Mater. 2017; 1700228.
Optimal light-management
Developing new materials with higher transmission (ZnO, TiO2, SnO2)
Optimization of layer thinknesses (e.g. tunnel junction layer)
Light – trapping techniques
2 T > 4 T due to non-existance of air-ITO interface (less reflection on surface of Si-cell)
Optimal light-management
2T world record!!!
11.06.18
Texturing of all surfaces
Rear reflector and texturing (IR backscattering)
Sahli, F et Al. Fully textured monolithic perovskite/silicon tandem solar cells with 25.2% power conversion efficiency. Nat. Materials. 2018
Fabrication
Spin coating
Problems with fabricating functional layers on Si-cell as substrateAfter texturing – vapor deposition has to be usedTemperature problems – TiO2 mesoporous layer (400 °C) – degradation of a:Si surface passivated layers of bottom cell
Wu Y et Al. Monolithic perovskite/silicon-homojunction tandem solar cell. Energy Environ. 2017; Sci. 10: 2472
Fabrication
Sputtering of ITO electrodes can damage perovskite
Addition of low-work-function metal-oxides
ZnO, TiO2, SnO2
Increases thermal and environmental (encapsulation) stability
Bush, K A et Al. 23.6%-efficient monolithic perovskite/silicon tandem solar cells with improved stability. Nat. Energy. 2017; 2 : 17009
Going to modules
4T cells mechanically stacked
Problematic size of individual perovskite solar cell ( < 1 cm2 )
Trade-off between sheet resistance of electrode and transparent electrodes thickness
Jaysankar M et Al. Four-Terminal Perovskite/Silicon Multijunction Solar Modules. Adv. Energy Mater. 2017; 7: 1602807
Going to modules
Cell-on-cell or module-on-module architectures
Jaysankar M et Al. Four-Terminal Perovskite/Silicon Multijunction Solar Modules. Adv. Energy Mater. 2017; 7: 1602807
Going to modules
Perovskite solar cells generally produced on flat glass surface (high-reflection)
Need for patterning surfaces of both cells
AR – pyramids attached to the glass surface
Refractive index matching layer (IML) between stacked cells
Jaysankar M et Al. Perovskite-silicon tandem solar modules with optimised light harvesting. Energy Environ. Sci. 2018.
Going to modules
Jaysankar M et Al. Perovskite-silicon tandem solar modules with optimised light harvesting. Energy Environ. Sci. 2018.
Conclusion
Perovskite / Si tandems as one of the most probable candidates for solar cells of future
Rapidly growing research field
Optimized modules in the beginning of research
Comercial production still far away
Thank you for your attention!
Questions?