Thienothiophene based polymers for organic solar cell with highest efficiencyLuping Yu, University of Chicago, DMR 1004195

Efficient and cost effective utilization of solar energy by using photovoltaic technology is one of the most important ways to tackle growing global energy problems. The organic bulk heterojunction (BHJ) materials are promising alternatives to semiconductors. Yu’s group have developed novel semiconducting polymer systems that exhibit power conversion efficiency above 8%. In order to further push the solar power output, this NSF grant supports research in development of new materials. An important issue is how to enhance the charge carriers mobility. We are investigating the effect of dimensionality of -systems. Thieno[3,4-b]thiophene unit has been proven to play an important role in achieving high power conversion efficiency. New polymers (PTTATT-1) containing tetrathienoanthracene were thus developed and showed very promising solar cell properties. Using the PTTATT-1/PC61BM as active film spin-coated from chloroform solution, a PCE of 5.6% was achieved. This new monomer with 2-D extended -conjugated unit will be further incorporated into other polymer system to establish structure/property relationship.

Voc (V)

Jsc (mA/cm2)

FF (%)

PCE (%)

PTB7/PC71BM* 0.74 14.6 68.6 7.4

PTTATT-1/PC61BM# 0.66 15.0 58.0 5.6

*solution prepared from dichlorobenzene/diiodooctance (97/3, v/v) #solution prepared from chloroform/diiodooctance (97/2, v/v)

The structures of polymers

The summary of solar cell devices

S

S

S

S

R2

R2

S

S F

n

COOR1

R1 = 2-ethylhexyl,R2 = 2-ethylhexyloxy

S

S

R2

R2

S

S

R1OOC

nF

PTB7

R1 = 2-ethylhexyl,R2 = 2-butylhexyl

PTTATT-1

Education: Under this grant, one student, Yongye Liang, has completed his Ph. D. research and graduated in last October, who has also received the Graduate Student Silver Award from the Materials Research Society because of his outstanding work supported by this grant. Three graduate students Hae Jung Son, Bridget Carsten and Tao Xu are working in this project. Two post-doctoral scientists has joined this project: Dr. Wei Wang and Dr. Feng He. An female undergraduate student, Ray Claire is also involved in this project.

Outreach: The PI has established close collaboration with a start-up company-Solarmer Energy for solar cell devices based on materials developed in PI’s lab (Dr. Gang Li). The company has offered financial support for this project as well as technical assistance in solar cell fabrication. Most recently, Intel has approved financial support for this PI’s exploration in solar materials. The PI also enjoys close collaborations with several research groups and national and industrial labs: Prof Tobin J. Marks at Northwest University on device fabrication and characterization; Dr. Lin Chen at Argonne National Lab (ANL) on electronic dynamics of low band gap polymers; Prof. Ivan Oleynik at U. of South Florida on theoretical studies, Prof. N. J. Tao at Arizona State University on molecular electronics; Dr. D.J. Liu at ANL on hydrogen storage polymers. General Motor has signed a contractor with PI on development of H2 storage polymers.

Solarmer Energy Inc. expects sun to shine on Chicago invention (Luping Yu (right) and Yongye

Liang display their new polymer device)

Thienothiophene based polymers for organic solar cell with highest efficiencyLuping Yu, University of Chicago, DMR 1004195

http://news.uchicago.edu/news.php?asset_id=1531