Challenges In Organic Solar Cell Research

Challenges in Polymer Solar Cell Research Thuc-Quyen Nguyen Department of Chemistry and Biochemistry Center for Polymers and Organic Solids (CPOS) University of California, Santa Barbara

Materials 1) Batch to batch variation - Molecular weight (MW) - Polydispersity - Chain end variation

Low MW 3.2 kD μh ~ 10-5 cm2/V.s

2) Impurity 3) Difficult to purify 4) Weak molecular packing

*

S

n

*

P3HT

High MW 33 kD μh ~ 10-3 cm2/V.s

Mike McGehee, Stanford University

Device Performance from Different P3HT Batches

Characterization: Internal Structures of the Bulk Heterojunction (BHJ) glass transparent electrode +

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100 nm metal electrode

Jenny Nelson, Current Opinion in Solid State and Materials Science 6 (2002) 87.

F. Yang, et al. Nature Mater. 4, 39 (2005)

R. Jansen

Alan Heeger et al. Science 270 (1995) 1789.

Cross Sectional TEM Images of P3HT:PCBM defoc = -5.02 μm

defoc = -9.31 μm

defoc = -18.85 μm

Images were collected at the same location using different defocused levels

Cross Sectional TEM Images of Pure Conjugated Polymer Film

O

MEH-PPV O

n

TEM Images of Polymer Grid Coating -3.59

-6.45

-12.65

Images were collected at the same location using different defocused levels