TY - JOUR

T1 - Interfacial Molecular Packing Determines Exciton Dynamics in Molecular Heterostructures

T2 - The Case of Pentacene-Perfluoropentacene

AU - Rinn, Andre

AU - Breuer, Tobias

AU - Wiegand, Julia

AU - Beck, Michael

AU - Hübner, Jens

AU - Döring, Robin C.

AU - Oestreich, Michael

AU - Heimbrodt, Wolfram

AU - Witte, Gregor

AU - Chatterjee, Sangam

N1 - Funding information: J.W. and M.B. acknowledge financial support by the DFG research training group RTG1991. Financial support was provided through SFB 1083 Structure and Dynamics of Internal Interfaces. Additionally, S.C. acknowledges financial support through the Heisenberg program of the German Science Foundation (CH660/2). J.W. and M.B. acknowledge financial support by the DFG research training group RTG1991. Financial support was provided through SFB 1083 “Structure and Dynamics of Internal Interfaces”. Additionally, S.C. acknowledges financial support through the Heisenberg program of the German Science Foundation (CH660/2).

PY - 2017/11/14

Y1 - 2017/11/14

N2 - The great majority of electronic and optoelectronic devices depend on interfaces between p-type and n-type semiconductors. Finding matching donor-acceptor systems in molecular semiconductors remains a challenging endeavor because structurally compatible molecules may not necessarily be suitable with respect to their optical and electronic properties, and the large exciton binding energy in these materials may favor bound electron-hole pairs rather than free carriers or charge transfer at an interface. Regardless, interfacial charge-transfer exciton states are commonly considered as an intermediate step to achieve exciton dissociation. The formation efficiency and decay dynamics of such states will strongly depend on the molecular makeup of the interface, especially the relative alignment of donor and acceptor molecules. Structurally well-defined pentacene-perfluoropentacene heterostructures of different molecular orientations are virtually ideal model systems to study the interrelation between molecular packing motifs at the interface and their electronic properties. Comparing the emission dynamics of the heterosystems and the corresponding unitary films enables accurate assignment of every observable emission signal in the heterosystems. These heterosystems feature two characteristic interface-specific luminescence channels at around 1.4 and 1.5 eV that are not observed in the unitary samples. Their emission strength strongly depends on the molecular alignment of the respective donor and acceptor molecules, emphasizing the importance of structural control for device construction.

AB - The great majority of electronic and optoelectronic devices depend on interfaces between p-type and n-type semiconductors. Finding matching donor-acceptor systems in molecular semiconductors remains a challenging endeavor because structurally compatible molecules may not necessarily be suitable with respect to their optical and electronic properties, and the large exciton binding energy in these materials may favor bound electron-hole pairs rather than free carriers or charge transfer at an interface. Regardless, interfacial charge-transfer exciton states are commonly considered as an intermediate step to achieve exciton dissociation. The formation efficiency and decay dynamics of such states will strongly depend on the molecular makeup of the interface, especially the relative alignment of donor and acceptor molecules. Structurally well-defined pentacene-perfluoropentacene heterostructures of different molecular orientations are virtually ideal model systems to study the interrelation between molecular packing motifs at the interface and their electronic properties. Comparing the emission dynamics of the heterosystems and the corresponding unitary films enables accurate assignment of every observable emission signal in the heterosystems. These heterosystems feature two characteristic interface-specific luminescence channels at around 1.4 and 1.5 eV that are not observed in the unitary samples. Their emission strength strongly depends on the molecular alignment of the respective donor and acceptor molecules, emphasizing the importance of structural control for device construction.

KW - charge-transfer excitations

KW - exciton dynamics

KW - molecular crystals

KW - organic heterostructures

KW - organic thin films

UR - http://www.scopus.com/inward/record.url?scp=85037709979&partnerID=8YFLogxK

U2 - 10.1021/acsami.7b11118

DO - 10.1021/acsami.7b11118

M3 - Article

C2 - 29135216

AN - SCOPUS:85037709979

VL - 9

SP - 42020

EP - 42028

JO - ACS Applied Materials and Interfaces

JF - ACS Applied Materials and Interfaces

SN - 1944-8244

IS - 48

ER -