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Adding Interstitial Layers For Improved Open-Circuit Voltage in Organic Solar Cells . Husna Anwar ’15 Arango Lab Leap Symposium 2013. SUNNY WITH A CHANCE OF POWER:. What’s the big deal?. CO2 levels are at 400 parts per million (ppm) in the atmosphere – . What’s the big deal?.
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Adding Interstitial Layers For Improved Open-Circuit Voltage in Organic Solar Cells Husna Anwar ’15 Arango Lab Leap Symposium 2013 SUNNY WITH A CHANCE OF POWER:
What’s the big deal? • CO2 levels are at 400 parts per million (ppm) in the atmosphere –
What’s the big deal? • - at 450 ppm temperatures will rise by 2 °C
What’s the big deal? • Fossil Fuels are a finite resource
What’s the big deal? • Fossil Fuels are a finite resource Alberta Tar Sands Image: National Geographic
Why Organic Photovoltaics (PV) Silicon-based panels are bulky, expensive and difficult to produce and install. Image: Birmingham Mail Image: Birmingham Mail
Why Organic Photovoltaics (PV) Silicon-based panels are bulky, expensive and difficult to produce and install. Image: Birmingham Mail Image: Birmingham Mail Organic PV is light-weight, flexible and can be produced in a matter of hours. Image:SoloPower Image: SoloPower Image: SoloPower
Why Organic Photovoltaics (PV) Image: Global Solar
Why Organic Photovoltaics (PV) Image: Global Solar Image: Global Solar Image: Global Solar Image: Global Solar
Why Organic Photovoltaics (PV) Image: Global Solar Image: Global Solar Image: Global Solar Image: Global Solar Image: Global Solar
The Donor/Acceptor Concept Donor Acceptor Image: Phoebe Tengdin
The Donor/Acceptor Concept Donor Acceptor Image: Phoebe Tengdin
The Donor/Acceptor Concept Photocurrent generation Electrons 1 Holes Image: Phoebe Tengdin
Voltage and Current • Current is the flow of charge
Voltage and Current • Current is the flow of charge • Voltage is what drives charge to flow
Voltage and Current • Current is the flow of charge • Voltage is what drives charge to flow • Power depends on both current and voltageP=IV
Issues with Organic PV • Low efficiency due to low open-circuit voltage (Voc)
Issues with Organic Solar • Low efficiency due to low open-circuit voltage (Voc) • Vocis connected to interfacial bandgap
Issues with Organic Solar • Low efficiency due to low open-circuit voltage (Voc) • Vocis connected to interfacial bandgap -3.0 eV LUMO -4.0 eV P3HT VOCdepends on interfacial bandgap PCBM HOMO -4.9 eV -6.5 eV
Deposition methods • Spin-coating Spinning Materialdropped Substrate B C D A Image: Andrea Miranda
Deposition methods • Vapor Deposition Coated substrate Substrate Material evaporates Material Thermal Evaporator(under vacuum) B C A Image: Sophia Weeks
Deposition methods • Transfer Printing Glass PCBM spin-coated ITO PEDOT:PSS P3HT PCBM PDMS B C D A
What we did • Vapor deposition of small molecule with a wide bandgap LUMO P3HT Charge recombination at the interface PCBM HOMO
What we did • Vapor deposition of small molecule with a wide bandgap very thin interstitial layer of Alq3 -3.1 eV -3.0 eV LUMO -4.0 eV P3HT Alq3 PCBM HOMO -4.9 eV -5.7 eV -6.5 eV
Results dark light
Results Voc=0.27 V Jsc=0.013 mA
Results Jsc=-0.011 mA Voc=0.27 V Voc=0.44 V Jsc=0.013 mA
Issues • Very low short-circuit current (Jsc)
Issues • Very low short-circuit current (Jsc) • Inconsistent device performance
Issues • Very low short-circuit current (Jsc) • Inconsistent device performance PCBM film on a PDMS stamp
Issues • Very low short-circuit current (Jsc) • Inconsistent device performance 68 nm -29 nm 10 nm 5 nm 5 nm 0 nm 0 nm Surface topography imaged through Atomic Force Microscopy (AFM) PCBM film on a PDMS stamp
What we found out • Alternative energy is essential
What we found out • Alternative energy is essential • Organic PV is a very viable solution
What we found out • Alternative energy is essential • Organic PV is a very viable solution • Adding a small molecule almost doubled our Voc
What we found out • Alternative energy is essential • Organic PV is a very viable solution • Adding a small molecule almost doubled our Voc • We need better Jsc and consistency
What we found out • Alternative energy is essential • Organic PV is a very viable solution • Adding a small moleculealmost doubled our Voc • We need better Jsc and consistency • We all want this jacket for when our phones die: Image: Crunch Wear
Future Work • Vapor deposition of C60 instead of PCBM for consistency -3.1 eV -3.0 eV LUMO Buckministerfullerene (C60) can be vapor deposited for uniform films -4.5 eV P3HT Alq3 C60 HOMO -4.9 eV -5.7 eV -6.2 eV
The people who made this summer awesome… • Professor Alexi Arango,Kanchi Gashaw and Ednah Louie • Sarah Byrne, Len and Thomas • Mount Holyoke College Image: Alexi Arango