More Like this

1. Cove‐Edge Nanoribbon Materials for Efficient Inverted Halide Perovskite Solar Cells

   https://doi.org/10.1002/anie.201706895  

   Castro, Edison ; Sisto, Thomas J. ; Romero, Elkin L. ; Liu, Fang ; Peurifoy, Samuel R. ; Wang, Jue ; Zhu, Xiaoyang ; Nuckolls, Colin ; Echegoyen, Luis ( October 2017 , Angewandte Chemie International Edition)

   Two cove‐edge graphene nanoribbons hPDI2‐Pyr‐hPDI2 (1) and hPDI3‐Pyr‐hPDI3 (2) are used as efficient electron‐transporting materials (ETMs) in inverted planar perovskite solar cells (PSCs). Devices based on the new graphene nanoribbons exhibit maximum power‐conversion efficiencies (PCEs) of 15.6 % and 16.5 % for1and2, respectively, while a maximum PCE of 14.9 % is achieved with devices based on [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM). The interfacial effects induced by these new materials are studied using photoluminescence (PL), and we find that1and2act as efficient electron‐extraction materials. Additionally, compared with PC₆₁BM, these new materials are more hydrophobic and have slightly higher LUMO energy levels, thus providing better device performance and higher device stability.

    

   more » « less
2. Balanced Charge Transport Optimizes Industry‐Relevant Ternary Polymer Solar Cells

   https://doi.org/10.1002/solr.202000538  

   Szymanski, Robin ; Henry, Reece ; Stuard, Samuel ; Vongsaysy, Uyxing ; Courtel, Stéphanie ; Vellutini, Luc ; Bertrand, Mélanie ; Ade, Harald ; Chambon, Sylvain ; Wantz, Guillaume ( October 2020 , Solar RRL)

   Bulk heterojunction polymer solar cells based on a novel combination of materials are fabricated using industry‐compliant conditions for large area manufacturing. The relatively low‐cost polymer PTQ10 is paired with the nonfullerene acceptor 4TIC‐4F. Devices are processed using a nonhalogenated solvent to comply with industrial usage in absence of any thermal treatment to minimize the energy footprint of the fabrication. No solvent additive is used. Adding the well‐known and low‐cost fullerene derivative PC₆₁BM acceptor to this binary blend to form a ternary blend, the power conversion efficiency (PCE) is improved from 8.4% to 9.9% due to increased fill factor (FF) and open‐circuit voltage (V_OC) while simultaneously improving the stability. The introduction of PC₆₁BM is able to balance the hole–electron mobility in the ternary blends, which is favourable for high FF. This charge transport behavior is correlated with the bulk heterojunction (BHJ) morphology deduced from grazing‐incidence wide‐angle X‐ray scattering (GIWAXS), atomic force microscopy (AFM), and surface energy analysis. In addition, the industrial figure of merit (i‐FOM) of this ternary blend is found to increase drastically upon addition of PC₆₁BM due to an increased performance–stability–cost balance.

    

   more » « less
3. A new family of liquid and solid guanidine-based n-type dopants for solution-processed perovskite solar cells

   https://doi.org/10.1039/D0QM00437E  

   Nakayama, Hidenori ; Schneider, Julia A. ; Faust, Mina ; Wang, Hengbin ; Read de Alaniz, Javier ; Chabinyc, Michael L. ( January 2020 , Materials Chemistry Frontiers)

   We present a series of new dopants based on a bicyclcic guanidine-type structure, 1,5,7-triazabicyclo[4.4.0]dec-5-ene ( TBD ), for organic semiconductors. A series of TBD derivatives that were alkylated at the 7-position were synthesized and their physical properties were determined. These stable dopants were shown to be effective n-type dopants for [6,6]-phenyl- C 61 -butyric acid methyl ester (PC 61 BM), poly{[ N , N ′-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]- alt -5,5′-(2,2′-bithiophene)} (P(NDI2OD-T2)) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3- d :2′,3′- d ′]- s -indaceno[1,2- b :5,6- b ′]dithiophene (ITIC). Films of PC 61 BM doped with 10 mol% of a dimeric derivative of TBD had electrical conductivities of 0.065 S cm −1 . The utility of the dopants was further shown by doping electron transport layers of PC 61 BM with 2TBD-C10 for methyl ammonium lead iodide (MAPbI 3 ) solar cells leading to improved fill factors and PCEs relative to undoped ETLs. 

   more » « less
4. Bipyridine‐Containing Host Materials for High Performance Yellow Thermally Activated Delayed Fluorescence‐Based Organic Light Emitting Diodes with Very Low Efficiency Roll‐Off

   https://doi.org/10.1002/adom.201901283  

   Chen, Dongyang ; Rajamalli, Pachaiyappan ; Tenopala‐Carmona, Francisco ; Carpenter‐Warren, Cameron L. ; Cordes, David B. ; Keum, Chang‐Min ; Slawin, Alexandra M. Z. ; Gather, Malte C. ; Zysman‐Colman, Eli ( November 2019 , Advanced Optical Materials)

   Two bipolar host materials3‐CBPyand4‐mCBPyare reported. These hosts are structural analogs of the common host materials CBP and mCBP wherein the phenyl rings have been replaced with pyridines. The two materials possess deep highest occupied molecular orbital (HOMO) and shallow lowest unoccupied molecular orbital (LUMO) levels along with sufficiently high energyS₁andT₁states that make them suitable hosts for yellow emitters in electroluminescent devices. Yellow‐emitting thermally activated delayed fluorescence organic light‐emitting diodes are fabricated using 2,4,6‐tris (4‐(10H‐phenoxazin‐10‐yl)phenyl)‐1,3,5‐triazine (tri‐PXZ‐TRZ) as the dopant emitter with either3‐CBPyor4‐mCBPyemployed as the host. Their device performance is compared to analogous devices using CBP and mCBP as host materials. The pyridine‐containing host devices show markedly improved external quantum efficiencies (EQE) and decreased roll‐off. The 7 wt% tri‐PXZ‐TRZ‐doped device exhibits very low turn‐on voltage (2.5 V for both3‐CBPyand4‐mCBPy) along with maximum external quantum efficiencies (EQE_max) reaching 15.6% (for3‐CBPy) and 19.4% (for4‐mCBPy). The device using4‐mCBPyalso exhibits very low efficiency roll‐off with an EQE of 16.0% at a luminance of 10 000 cd m⁻².

    

   more » « less
5. Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

   https://doi.org/10.3762/bjoc.19.121  

   Mohapatra, Swagat K ; Al Kurdi, Khaled ; Jhulki, Samik ; Bogdanov, Georgii ; Bacsa, John ; Conte, Maxwell ; Timofeeva, Tatiana V ; Marder, Seth R ; Barlow, Stephen ( January 2023 , Beilstein Journal of Organic Chemistry)

   1,3-Dimethyl-2,3-dihydrobenzo[d]imidazoles,1H, and 1,1',3,3'-tetramethyl-2,2',3,3'-tetrahydro-2,2'-bibenzo[d]imidazoles,1₂, are of interest as n-dopants for organic electron-transport materials. Salts of 2-(4-(dimethylamino)phenyl)-4,7-dimethoxy-, 2-cyclohexyl-4,7-dimethoxy-, and 2-(5-(dimethylamino)thiophen-2-yl)benzo[d]imidazolium (1g–i⁺, respectively) have been synthesized and reduced with NaBH₄to1gH,1hH, and1iH, and with Na:Hg to1g₂and1h₂. Their electrochemistry and reactivity were compared to those derived from 2-(4-(dimethylamino)phenyl)- (1b⁺) and 2-cyclohexylbenzo[d]imidazolium (1e⁺) salts.E(1⁺/1^•) values for 2-aryl species are less reducing than for 2-alkyl analogues, i.e., the radicals are stabilized more by aryl groups than the cations, while 4,7-dimethoxy substitution leads to more reducingE(1⁺/1^•) values, as well as cathodic shifts inE(1₂^•+/1₂) andE(1H^•+/1H) values. Both the use of 3,4-dimethoxy and 2-aryl substituents accelerates the reaction of the1Hspecies with PC₆₁BM. Because 2-aryl groups stabilize radicals,1b₂and1g₂exhibit weaker bonds than1e₂and1h₂and thus react with 6,13-bis(triisopropylsilylethynyl)pentacene (VII) via a “cleavage-first” pathway, while1e₂and1h₂react only via “electron-transfer-first”.1h₂exhibits the most cathodicE(1₂^•+/1₂) value of the dimers considered here and, therefore, reacts more rapidly than any of the other dimers withVIIvia “electron-transfer-first”. Crystal structures show rather long central C–C bonds for1b₂(1.5899(11) and 1.6194(8) Å) and1h₂(1.6299(13) Å).

    

   more » « less