This document discusses how the performance of organic solar cells is affected by the incident angle of sunlight. It presents experimental data showing how reflection spectra change with varying incidence angles, and compares this to simulations. Key findings include: 1) Simulation and experiment agree that most spectral features remain largely unchanged across a range of incidence angles, though absorption peaks can shift up to 40nm. 2) A generalized simulation model is developed that can predict reflection spectra for any incident angle, matching experimental observations. 3) While performance varies some with changing sunlight angles through the day and seasons, organic solar cells maintain efficiency relatively well compared to conventional silicon cells.

1. Incidence Angle Dependence of Organic Solar CellsVincent DeGeorge1, Brent Valle2, Kenneth Singer PhD. 21)Dept. of Physics, John Carroll University, University Heights OH 2) Dept. of Physics, Case Western Reserve University, Cleveland OH

2. Introduction and BackgroundM. A. Green, Third generation photovoltaics. Springer (2003).1st Generation: Bulk Silicon/semiconductor substrates

3. 2nd Generation: Thin film compound semiconductors

4. 3rd Generation: Organic Polymer materialsOrganic PhotovoltaicsElectrodePCBMP3HTLUMOElectrodePhoton absorption, creation of excitonExciton DiffusionElectron/Hole separation at interfaceCharge transport along polymer chainCharge collection at electrodesEFHOMOn/donorp/acceptor

5. ITOP.V.AlDevice Structure1inchCertain material thicknesses produce optical cavity resonanceReflectedIncident102 nm

6. MotivationThe incident angle of the sun varies throughout the day and season

7. How is the performance of the cell effected by non-normal incidence? Optical cavity resonance?12:00 pm4:00 pm90°30°Solar Panel

8. TheoryLayer/Phase Matrix, L, and Interface Matrix, I, depend on: Refraction index, n Absorption index, kIncidence Angle, φThickness, dInt1Int2Int3Int4Ambientlayer1layer2Substratelayer3n1φd2k1

9. Computation

10. Experimental SetupCARY Spectrophotometer used to measure normal reflectance

11. Ocean Optics light source and spectrophotometer supplied and detected light to and from the sample respectively