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 Image: National Geographic Alberta Tar Sands

Why Organic Photovoltaics (PV) Silicon-based panels are bulky, expensive and difficult to produce and install. Image: Birmingham Mail

Why Organic Photovoltaics (PV) Silicon-based panels are bulky, expensive and difficult to produce and install. Organic PV is light-weight, flexible and can be produced in a matter of hours. Image:SoloPower Image: Birmingham Mail Image: SoloPower Image: Birmingham Mail Image: SoloPower

Why Organic Photovoltaics (PV) Image: Global Solar

Why Organic Photovoltaics (PV) Image: Global Solar

Why Organic Photovoltaics (PV) Image: Global Solar

The Donor/Acceptor Concept Image: Phoebe Tengdin Donor Acceptor

The Donor/Acceptor Concept Image: Phoebe Tengdin Donor Acceptor

The Donor/Acceptor Concept Image: Phoebe Tengdin 1 Photocurrent generation Electrons Holes

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 voltage P=IV

Issues with Organic PV Low efficiency due to low open-circuit voltage (V oc )

Issues with Organic Solar Low efficiency due to low open-circuit voltage (V oc ) V oc is connected to interfacial bandgap

Issues with Organic Solar Low efficiency due to low open-circuit voltage (V oc ) V oc is connected to interfacial bandgap -3.0 eV -4.9 eV V OC depends on interfacial bandgap LUMO HOMO P3HT PCBM -4.0 eV -6.5 eV

Deposition methods Spin-coating A BCD Image: Andrea Miranda Substrate Material dropped Spinning

Deposition methods Vapor Deposition A BC Substrate Material Thermal Evaporator (under vacuum) Material evaporates Coated substrate Image: Sophia Weeks

Deposition methods Transfer Printing PDMS PCBM Glass PEDOT:PSS P3HT PCBM spin- coated A BCD ITO

What we did Vapor deposition of small molecule with a wide bandgap LUMO HOMO P3HT PCBM Charge recombination at the interface

What we did Vapor deposition of small molecule with a wide bandgap -3.0 eV -4.9 eV -3.1 eV -4.0 eV -5.7 eV -6.5 eV LUMO HOMO P3HT Alq3 PCBM very thin interstitial layer of Alq3

Results dark light

Results Voc =0.27 V Jsc = mA

Results Voc =0.44 V Voc =0.27 V Jsc = mA Jsc = mA

Issues Very low short-circuit current (J sc )

Issues Very low short-circuit current (J sc ) Inconsistent device performance

Issues Very low short-circuit current (J sc ) Inconsistent device performance PCBM film on a PDMS stamp

Issues Very low short-circuit current (J sc ) Inconsistent device performance Surface topography imaged through Atomic Force Microscopy (AFM) PCBM film on a PDMS stamp -29 nm 68 nm 5 nm 10 nm 0 nm

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 V oc

What we found out Alternative energy is essential Organic PV is a very viable solution Adding a small molecule almost doubled our V oc We need better Jsc and consistency

What we found out Alternative energy is essential Organic PV is a very viable solution Adding a small molecule almost doubled our V oc We need better J sc 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 -3.0 eV -4.9 eV -3.1 eV -4.5 eV -5.7 eV LUMO HOMO P3HT Alq3 C eV Buckministerfullerene (C60) can be vapor deposited for uniform films

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