TY - JOUR
T1 - Molecular doping of regioregular poly(3-hexylthiophene) layers by 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane investigated by infrared spectroscopy and electrical measurements
AU - Tadaki, Daisuke
AU - Ma, Teng
AU - Zhang, Jinyu
AU - Iino, Shohei
AU - Hirano-Iwata, Ayumi
AU - Kimura, Yasuo
AU - Niwano, Michio
N1 - Publisher Copyright:
© 2015 The Japan Society of Applied Physics.
PY - 2015/9/1
Y1 - 2015/9/1
N2 - Molecular doping is a charge-transfer process intended to improve the performance of organic electronic devices such as organic transistors. We have investigated molecular doping of regioregular poly(3-hexylthiophene) (P3HT) layers by 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) using infrared absorption spectroscopy in the multiple internal reflection geometry (MIR-IRAS) and conductivity measurements. IRAS data confirm that F4-TCNQ acts as an effective p-type dopant for P3HT; highly doped P3HT displayed an intense, broad absorption band due to polaron ("polaron band") and a high carrier (hole) density which are indicative of the charge transfer between F4-TCNQ and P3HT. We demonstrate that the charge (hole) transferred from the dopant molecule is distributed along the P3HT polymer chain and spreads over at least 10 thiophene monomer units on the chain. From a comparison of the measured conductivity of F4-TCNQ-doped P3HT layers with the carrier density, we show that the carrier mobility is proportional to the concentration of carriers (holes), which suggests that F4-TCNQ doping induces the conformational change of P3HT polymer chains to enhance the mobility of holes in the films of the doped P3HTs.
AB - Molecular doping is a charge-transfer process intended to improve the performance of organic electronic devices such as organic transistors. We have investigated molecular doping of regioregular poly(3-hexylthiophene) (P3HT) layers by 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) using infrared absorption spectroscopy in the multiple internal reflection geometry (MIR-IRAS) and conductivity measurements. IRAS data confirm that F4-TCNQ acts as an effective p-type dopant for P3HT; highly doped P3HT displayed an intense, broad absorption band due to polaron ("polaron band") and a high carrier (hole) density which are indicative of the charge transfer between F4-TCNQ and P3HT. We demonstrate that the charge (hole) transferred from the dopant molecule is distributed along the P3HT polymer chain and spreads over at least 10 thiophene monomer units on the chain. From a comparison of the measured conductivity of F4-TCNQ-doped P3HT layers with the carrier density, we show that the carrier mobility is proportional to the concentration of carriers (holes), which suggests that F4-TCNQ doping induces the conformational change of P3HT polymer chains to enhance the mobility of holes in the films of the doped P3HTs.
UR - http://www.scopus.com/inward/record.url?scp=84940971231&partnerID=8YFLogxK
U2 - 10.7567/JJAP.54.091602
DO - 10.7567/JJAP.54.091602
M3 - Article
AN - SCOPUS:84940971231
SN - 0021-4922
VL - 54
JO - Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
JF - Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
IS - 9
M1 - 091602
ER -