Premium
Real‐Time Investigation of Crystallization and Phase‐Segregation Dynamics in P3HT:PCBM Solar Cells During Thermal Annealing
Author(s) -
Agostinelli Tiziano,
Lilliu Samuele,
Labram John G.,
CampoyQuiles Mariano,
Hampton Mark,
Pires Ellis,
Rawle Jonathan,
Bikondoa Oier,
Bradley Donal D. C.,
Anthopoulos Thomas D.,
Nelson Jenny,
Macdonald J. Emyr
Publication year - 2011
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201002076
Subject(s) - materials science , crystallization , annealing (glass) , photocurrent , solar cell , chemical engineering , diffraction , polymer solar cell , crystallization of polymers , optoelectronics , polymer , optics , composite material , physics , engineering
Crystallization and phase segregation during thermal annealing lead to the increase of power‐conversion efficiency in poly(3‐hexylthiophene) (P3HT):[6,6]‐phenyl C61‐butyric acid methyl ester (PCBM) bulk‐heterojunction solar cells. An understanding of the length and time scale on which crystallization and phase segregation occur is important to improve control of the nanomorphology. Crystallization is monitored by means of grazing incidence X‐ray diffraction in real time during thermal annealing. Furthermore, the change in film density is monitored by means of ellipsometry and the evolution of carrier mobilities by means of field effect transistors, both during annealing. From the combination of such measurements with those of device performance as a function of annealing time, it is concluded that the evolution of microstructure involves two important time windows: i) A first one of about 5 minutes duration wherein crystallization of the polymer correlates with a major increase of photocurrent; ii) a second window of about 30 minutes during which the aggregation of PCBM continues, accompanied by an increase in the fill factor.