Ghani, F.F.GhaniOpitz, A.A.OpitzPingel, P.P.PingelHeimel, G.G.HeimelSalzmann, I.I.SalzmannFrisch, J.J.FrischNeher, D.D.NeherTsami, A.A.TsamiScherf, U.U.ScherfKoch, N.N.Koch2022-03-042022-03-042015https://publica.fraunhofer.de/handle/publica/23923210.1002/polb.23631The electrical conductivity of organic semiconductors can be enhanced by orders of magnitude via doping with strong molecular electron acceptors or donors. Ground-state integer charge transfer and charge-transfer complex formation between organic semiconductors and molecular dopants have been suggested as the microscopic mechanisms causing these profound changes in electrical materials properties. Here, we study charge-transfer interactions between the common molecular p-dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane and a systematic series of thiophene-based copolymers by a combination of spectroscopic techniques and electrical measurements. Subtle variations in chemical structure are seen to significantly impact the nature of the charge-transfer species and the efficiency of the doping process, underlining the need for a more detailed understanding of the microscopic doping mechanism in organic semiconductors to reliably guide targeted chemical design.en547journal article