Powering Big Data and the IoT s

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1 Powering Big Data and the IoT s a great challenge and an even greater opportunity for materials efficiency using low cost perovskite solar cells Reinhold H. Dauskardt (dauskardt@stanford.edu) by 2020, it is expected that more than 28 billion IoT devices will be in operation...

2 Prepare for a Connected World where Everything Computes Smart devices create opportunities to gain faster insights by connecting the unconnected New ways to - conduct material discovery and drive materials efficiency - develop new business with greater insights - learn about the environment and enable sustainability - enable developing nations and their citizens Internet of Content (Distribution/Access) Information Entertainment Internet of Service (Participation/Trade) E-commerce Productivity tools Integrated chains Internet of People (Collaboration/Share) Voice and video collaboration Social media and docs Web logs/boards Internet of Things (Integration/Control) Indexing and tracking Control and connectivity Autonomous operations

3 Energy Is A Big And Rapidly Growing Problem For Big Data and the IoTs U.S. data centers use more than 90 billion kilowatt-hours of electricity a year, requiring roughly 34 giant (500-megawatt) coal-powered plants. Global data centers used roughly 416 terawatts (4.16 x watts) (or about 3% of the total electricity) last year, nearly 40% more than the entire United Kingdom. Consumption will double every four years Reported by Danilak, Forbes, Dec 2017.

4 Energy Is A Big And Rapidly Growing Problem For Big Data and the IoTs Billions of Machine-to-Machine devices in use today and an ever-increasing number of connected devices using low-power, low-throughput networks. Billions of additional point-of-use devices, from personal electronics, smart sensors for home and urban centers, traffic sensors and parking meters, and even technologically connected ecosystems, solar-powered parking meters generated >$230,000 for Los Angeles sensors under forest canopy for real-time forest monitoring (Perlis, northern most state of Malaysia) 2016 IEEE Student Conf Res Dev

5 Energy Is A Big And Rapidly Growing Problem For Big Data and the IoTs Comprehensive solution to the challenge of powering the IoT s: design of ultra-low power embedded hardware platforms intelligent system-level power management make devices self-powered by harvesting energy from their operating environment local energy harvesting is key, from thermoelectric, electrodynamic, vibration and motion, and from solar but low cost is an equally important driver 2016 IEEE Student Conf Res Dev

6 Sunshine is Plentiful and Inexhaustible Metal Halide Perovskites Next Generation Solar Cells tunable bandgap ev and excellent efficiency strong optical absorption (~1000x thinner than silicon) much greater materials efficiency tolerance to defects and grain boundaries solution processable with scalable-manufacturing make much cheaper Challenge Stability and reliability need new concepts in solar module processing and design perovskites so we can use longer

7 Perovskite Device Architectures Studied Al ZnO PCBM / MPMIC 60 CH 3 NH 3 PbI 3 PEDOT:PSS ITO-Glass Ag Spiro-OMeTAD CH 3 NH 3 Pb(I 1-x Br x ) 3 C 60 ctio 2 ITO-Glass Au Spiro-OMeTAD CH 3 NH 3 Pb(I 1-x Br x ) 3 mtio 2 /CH 3 NH 3 PbI 3 ctio 2 FTO-Glass Au PTAA CH 3 NH 3 Pb(I 1-x Br x ) 3 mtio 2 /CH 3 NH 3 PbI 3 ctio 2 FTO-Glass Ag P3HT CH 3 NH 3 PbI 3 ZnO ITO-Glass Ag P3HT CH 3 NH 3 PbI 3 ZnO ITO-PET Al PCBM CH 3 NH 3 PbI 3-x Cl x PEDOT:PSS ITO-Glass Acetate Perovskite (inverted) Acetate Perovskite (regular) Mesoporous Perovskite w/ Spiro Mesoporous Perovskite w/ PTAA Planar, Slot-Die Perovskite Planar, Rollto-Roll Perovskite Planar, Large Grain Perovskite Spin with air flow Air Spin with toluene drip N 2 Rollto-Roll toluene Slot-Die Hot-casting Precursor MAI/PbAcO 2 in DMF MAI/PbI 2 in GBL/DMSO PbI2 in DMF and MAI in 2-propanol MACl/PbI 2 in DMF Delivery Postdeposition Spin coated with compressed dry air flow Annealed in dry air at 100 C for 5 min 2-step spin coating process in N 2 with toluene drop-casted during second step Sequential slot-die coating in air of PbI 2 and MAI heated at 70 C Substrate heated before spin coating Annealed in nitrogen at 100 C for 10 min N 2 gas quench None Cooled on glass

8 Fundamental Challenge for Stability and Reliability Fracture Energy, G c (J/m 2 ) 1, Polymers for Packaging Encapsulation Dense SiO 2 TEOS SiO 2 Protective Coatings ULK dielectrics Human Skin (SC) Structural Materials Silicon PV Al doped ZnO CdS CuIn x Ga (1-x) Se 2 Mo Al foil CIGS Organics and OPV G c ~ 10 J/m 2 G c ~ 5 J/m Rolston, et al., Extreme Mechanics Letters, Rolston, et. al. Advanced Energy Materials, Perovskites

9 Rapid Spray Plasma Processing (RSPP) of Perovskites low-cost and scalable open-air processing with compressed air perovskites with improved optoelectronic properties and stability Hilt, Hovish, Rolston, Dauskardt, E&ES, 2018.

10 RSPP Produces Highly Efficient Devices C 60 /BCP RSPP Spin-coated PEDOT:PSS MAPbI 3 ITO Glass 15.7% Efficiency MAPbI 3 ITO Glass 15.4% Efficiency Normalized absorbance (a.u.) 1,00 0,75 0,50 0,25 0, Wavelength, (nm) RSPP Spin-coated Fracture Energy, G c (J/m 2 ) superior mechanical stability and fracture resistance 0.43 J m -2 spin coated hot-cast* 4.4 J m -2 RSPP Hilt, Hovish, Rolston, Dauskardt, E&ES, 2018.

11 Plasma Deposition of Silica Barriers Air Air HMDSO Barrier film Au PTAA MAPbI 3 1 Perovskite Solar Cell Moisture Stability SiO 2 Control Rolston, et.al. J. Mat. Chemistry A, TFT Normalized PCE C, 25% RH C 60 /TiO 2 ITO intact perovskite 25% TFT degraded perovskite control Exposure time (hr)

12 A Scaffold Concept for Reliability and Efficiency electrode Scaffold PTAA-X Perovskite m-cell Scaffold C 60 compact TiO 2 ITO-substrate Scaffold Reflective Electrode Sequential Scaffold Filling Transparent Electrode Encapsulant

13 A Scaffold Concept for Reliability and Efficiency Current Density (ma cm -2 ) scaffold wall width 200 µm 100 µm 50 µm planar laser beam induced current EQE Voltage (V) planar 17.9 ma 50 µm 14.3 ma 100 µm 12.1 ma µm 6.9 ma Wavelength, (nm)

14 Micro-Lens Array Design and Scaffold Fabrication lens arrays designed with optical modeling lens array used to fabricate solar cells fully self-aligning

15 Micro-Lens Array Design and Scaffold Fabrication without lenses with lenses mm mm mm mm

16 Micro-Lens Array Design and Scaffold Fabrication Angle of incidence: Passive tracking by lenses for increased diurnal power efficiency Fracture Energy, G c (J m -2 ) c-si/cigs modules Planar OPV Planar Perovskite Scaffold-Partitioned Perovskite lens array Efficiency, PCE (%)

17 Conclusions Big data has enormous potential to revolutionize materials discovery and efficiencies but, energy is a big and rapidly growing challenge for big data and the IoTs Make IoT devices self-powered by harvesting energy from their operating environment Sunshine is a plentiful and inexhaustible energy supply Perovskite solar cells are one of the most promising low-cost and efficient solar PV materials with significant potential for improved materials efficiency, but stability and reliability must be addressed New concepts in perovskite scalable spray-plasma processing and module design concepts for reliable solar PV enable the use of significantly less materials for longer