Transient photoconductivity in polymer bulk heterojunction solar cells. Competition between sweep-out and recombination

Journal Article · Tue Jan 18 04:00:00 EST 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.83.035205· OSTI ID:1064872

Cowan, Sarah ^[1]; Street, R. A. ^[2]; Cho, Shinuk ^[1]; Heeger, Alan ^[1]

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1. Univ. of California, Santa Barbara, CA (United States)
2. Palo Alto Research Center, CA (United States)

Transient photoconductivity measurements carried out on bulk heterojunction (BHJ) solar cells demonstrate the competition between carrier sweep-out by the internal field and the loss of photogenerated carriers by recombination. The transient photoconductance data imply the existence of a well-defined internal field; carrier sweep-out is proportional to the magnitude of the internal field and limited by the carrier mobility. At external voltages near open circuit where the internal field approaches zero, the photocurrent decays because of the recombination of photogenerated mobile carriers. Mobility and recombination lifetimes are evaluated for carriers in poly[3-hexylthiophene] (P3HT): [6,6]-phenyl-C₆₁ -butyric acid methyl ester (PC₆₀ BM) and poly[N -9''-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT): [6,6]-phenyl-C₇₁ -butyric acid methyl ester (PC₇₁ BM) solar cells.

• Research Organization: Energy Frontier Research Centers (EFRC); Center for Energy Efficient Materials (CEEM)
• Sponsoring Organization: USDOE SC Office of Basic Energy Sciences (SC-22)
• DOE Contract Number: SC0001009
• OSTI ID: 1064872
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Vol. 83; ISSN 1098-0121
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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