Benzochalcogenodiazole‐Based Donor–Acceptor–Acceptor Molecular Donors for Organic Solar Cells

Ting, Hao‐Chun; Chen, Yihong; Lin, Li‐Yen; Chou, Shu-Hua; Liu, Yi-Hung; Lin, Hao‐Wu; Wong, Ken‐Tsung

doi:10.1002/cssc.201301090

Cited by 37 publications

(34 citation statements)

References 63 publications

(82 reference statements)

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“…The observed morphological changes provide additional means for manipulating the bulk property as well as device performances by thermal processing. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 14 coplanar dimer is different from published examples, 17,[20][21][22][23][24] where "cofacial" antiparallel dimers via π-π stacking are observed. As shown in Figure 3c, the MIDTP molecule also adopts a π-π stacking motif with an interplane distance of ca.…”

Section: Synthesis and Propertiescontrasting

confidence: 48%

Cofacial Versus Coplanar Arrangement in Centrosymmetric Packing Dimers of Dipolar Small Molecules: Structural Effects on the Crystallization Behaviors and Optoelectronic Characteristics

Chou¹,

Kang

Chang

et al. 2016

ACS Appl. Mater. Interfaces

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Two D-π-A-A molecules (MIDTP and TIDTP) composed of an electron-rich ditolylamino group (D) and an electron-deficient 5-dicyanovinylenylpyrimidine (A-A) fragment bridged together with indeno[1,2-b]thiophene (IDT) were synthesized. These molecules provide an opportunity to examine in-depth the impact of side-chain variations (methyl vs p-tolyl) on the crystallization behaviors, solid-state morphology, physical properties, and optoelectronic characteristics relevant for practical applications. X-ray analyses on single-crystal structures indicate that methyl-substituted MIDTP forms "coplanar antiparallel dimers" via C-H···S interactions and organizes into an ordered slip-staircase arrays. In contrast, p-tolyl-bearing TIDTP shows "cofacial centrosymmetric dimers" via π-π interactions and packs into a less-ordered layered structures. The X-ray diffraction analyses upon thermal treatment are consistent with a superior crystallinity of MIDTP, as compared to that of TIDTP. This difference indicates a greater propensity to organization by introduction of the smaller methyl group versus the bulkier p-tolyl group. The increased propensity for order by MIDTP facilitates the crystallization of MIDTP in both solution-processed and vacuum-deposited thin films. MIDTP forms solution-processed single-crystal arrays that deliver OFET hole mobility of 6.56 × 10(-4) cm(2) V(-1) s(-1), whereas TIDTP only forms amorhpous films that gave lower hole mobility of 1.34 × 10(-5) cm(2) V(-1) s(-1). MIDTP and TIDTP were utilized to serve as donors together with C70 as acceptor in the fabrication of small-molecule organic solar cells (SMOSCs) with planar heterojunction (PHJ) or planar-mixed heterojunction (PMHJ) device architectures. OPV devices based on higher crystalline MIDTP delivered power conversion efficiencies (PCEs) of 2.5% and 4.3% for PHJ and PMHJ device, respectively, which are higher than those of TIDTP-based cells. The improved PCEs of MIDTP-based devices are attributed to better hole-transport character.

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Section: Synthesis and Propertiescontrasting

confidence: 48%

Cofacial Versus Coplanar Arrangement in Centrosymmetric Packing Dimers of Dipolar Small Molecules: Structural Effects on the Crystallization Behaviors and Optoelectronic Characteristics

Chou¹,

Kang

Chang

et al. 2016

ACS Appl. Mater. Interfaces

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“…2b). 13,18 The J-V characteristics under 1 sun, AM1.5G illumination and the EQE vs.wavelength of In Fig. 4 we show the dependence of OPV performance on mixed layer thickness (l).…”

Section: Resultsmentioning

confidence: 99%

“…Electrostatic attraction between the large fixed internal dipoles in these molecules leads to formation of centrosymmetric dimers with cofacial π-π antiparallel alignment along the long molecular axis. 13,[16][17][18] The net result is that the total dipole moment is zero for these cofacial π-π dimers. The dimers of the d-a-a' molecules 2-[ (7-(4-[N,N-bis(4-methylphenyl)amino]phenyl)-2,1,3-benzothia-diazol-4-yl)methylene] propane-dinitrile (i.e.…”

mentioning

confidence: 99%

Charge transport and exciton dissociation in organic solar cells consisting of dipolar donors mixed withC70

et al. 2015

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We investigate dipolar donor materials mixed with a C 70 acceptor in an organic photovoltaic (OPV) cell. Dipolar donors that have donor-acceptor-acceptor (d-a-a') structure result in high conductivity pathways due to close coupling between neighboring molecules in the mixed films.We analyze the charge transfer properties of the dipolar donor:C 70 mixtures and corresponding neat donors using a combination of time-resolved electroluminescence from intermolecular polaron pair states and conductive tip atomic force microscopy, from which we infer that dimers of the d-a-a' donors tend to form a continuous network of nanocrystalline clusters within the blends. Additional insights are provided by quantum mechanical calculations of hole transfer coupling and hopping rates between donor molecules using nearest neighbor donor packing motifs taken from crystal structural data. The approximation using only nearest neighbor interactions leads to good agreement between donor hole hopping rates and the conductive properties of the donor:C 70 blends. This represents a significant simplification from requiring details of the nano-and mesoscale morphologies of thin films to estimate their electronic 2 characteristics. Using these dipolar donors, we obtain a maximum power conversion efficiency of 9.6 ± 0.5 % under 1 sun, AM1.5G simulated illumination for an OPV comprised of an active layer containing a dipolar donor mixed with C 70 .3

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“…Over the past a few years, a series of small‐molecule donors with a simple D‐A‐A structure have been synthesized by Wong and co‐workers for high‐efficiency vacuum‐deposition OSCs; in conjunction with the C 60 or C 70 acceptor, the highest power conversion efficiency (PCE) has reached 6.8% for a single junction cell, 10.0% and 11.1% for a tandem and a triple junction cell, respectively. Among these donor materials, 2‐{[7‐(5‐ N , N ‐ditolylaminothiophen‐2‐yl)‐2,1,3‐benzothiadiazol‐4‐yl]methylene}malononitrile (DTDCTB, see Figure a) has gained intensive attention .…”

mentioning

confidence: 99%

Deposition Growth and Morphologies of C₆₀ on DTDCTB Surfaces: An Atomistic Insight into the Integrated Impact of Surface Stability, Landscape, and Molecular Orientation

Han

Shen

2015

Adv Materials Inter

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residual Coulomb attraction with holes, enabling ultrafast charge separation. [ 21 ] Therefore, it is very important to understand and ultimately control the active layer morphologies and the D/A interface confi gurations at the molecular level. [8][9][10][11][12][13][14][15][17][18][19][20][21][22][23][24] Although modulation of the active layer morphologies has been successfully achieved by several different preparation procedures, [ 1,12,13,[25][26][27][28] it still remains experimentally diffi cult to accurately probe the molecular self-assembly processes and packing structures, [ 29 ] which severely hinders obtaining reliable structure-property relationships and further improving the device performance.Over the past a few years, a series of small-molecule donors with a simple D-A-A structure have been synthesized by Wong and co-workers for high-effi ciency vacuum-deposition OSCs; [30][31][32][33] in conjunction with the C 60 or C 70 acceptor, the highest power conversion effi ciency (PCE) has reached 6.8% for a single junction cell, [ 31 ] 10.0% and 11.1% for a tandem and a triple junction cell, [ 34 ] respectively. Among these donor materials, 2-{[7-(5-N , N -ditolylaminothiophen-2-yl)-2,1,3-benzothiadiazol-4-yl]methylene}malononitrile (DTDCTB, see Figure 1 a) has gained intensive attention. [ 30,31,[34][35][36][37][38][39][40][41][42] Here, interesting to us is the antiparallel packing mode in the DTDCTB crystal (see Figure 1 b), which can provide a variety of model surfaces with different features to systematically probe the infl uence of donor surfaces on the fullerene packing and interface morphologies.In this contribution, we have mimicked vapor-phase deposition and growth of C 60 on different DTDCTB substrate surfaces via nonequilibrium atomistic molecular dynamics (MD) simulations. [ 43,44 ] Using this scheme, Muccioli and co-workers have investigated the crystal growth of pentacene or sexithiophene on the C 60 (001) substrate, while the relationship between different surface properties and thin-fi lm morphologies is yet to be revealed. [ 43,44 ] Our simulated results point to that, both the interfacial and thin-fi lm morphologies substantially depend on a combinational role of the stability, ordering, landscape, and local molecular orientation of the substrate surfaces. This work will be helpful to understand and control the formation of crystalline fullerene in the active layer toward achieving effi cient separation of the photogenerated charges for organic photovoltaics.The initial DTDCTB substrate surfaces with different molecular orientations, i.e., nearly "fl at," "upright," and "edge-on" confi gurations (see Figure S1, Supporting Information) were constructed by cleaving the DTDCTB crystal along the (100), (010), and (001) crystallographic planes, respectively. Each type of confi guration has two opposite facets, labeled as A and B (i.e., obtained by cutting the cell at full and half cell, respectively), because the molecules stack in an antiparallel manner Organic solar cells offer considerab...

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Benzochalcogenodiazole‐Based Donor–Acceptor–Acceptor Molecular Donors for Organic Solar Cells

Cited by 37 publications

References 63 publications

Cofacial Versus Coplanar Arrangement in Centrosymmetric Packing Dimers of Dipolar Small Molecules: Structural Effects on the Crystallization Behaviors and Optoelectronic Characteristics

Cofacial Versus Coplanar Arrangement in Centrosymmetric Packing Dimers of Dipolar Small Molecules: Structural Effects on the Crystallization Behaviors and Optoelectronic Characteristics

Charge transport and exciton dissociation in organic solar cells consisting of dipolar donors mixed withC70

Deposition Growth and Morphologies of C₆₀ on DTDCTB Surfaces: An Atomistic Insight into the Integrated Impact of Surface Stability, Landscape, and Molecular Orientation

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Benzochalcogenodiazole‐Based Donor–Acceptor–Acceptor Molecular Donors for Organic Solar Cells

Cited by 37 publications

References 63 publications

Cofacial Versus Coplanar Arrangement in Centrosymmetric Packing Dimers of Dipolar Small Molecules: Structural Effects on the Crystallization Behaviors and Optoelectronic Characteristics

Cofacial Versus Coplanar Arrangement in Centrosymmetric Packing Dimers of Dipolar Small Molecules: Structural Effects on the Crystallization Behaviors and Optoelectronic Characteristics

Charge transport and exciton dissociation in organic solar cells consisting of dipolar donors mixed withC70

Deposition Growth and Morphologies of C60 on DTDCTB Surfaces: An Atomistic Insight into the Integrated Impact of Surface Stability, Landscape, and Molecular Orientation

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Deposition Growth and Morphologies of C₆₀ on DTDCTB Surfaces: An Atomistic Insight into the Integrated Impact of Surface Stability, Landscape, and Molecular Orientation