Chad Risko

Former Senior Research Scientist


Office: MS&E 4202

Phone: 404-385-8162


Publications in the Brédas Group:

  • Intermixing at the Pentacene-Fullerene Bilayer Interface: A Molecular Dynamics Study, Fu, YT; Risko, C; and Bredas, JL, Advanced Materials, 25, 878-882 [2013]
  • Bis(Carbazolyl) Derivatives of Pyrene and Tetrahydropyrene: Synthesis, Structures, Optical Properties, Electrochemistry, and Electroluminescence, Kaafarani, BR; El-Ballouli, AO; Trattnig, R; Fonari, A; Sax, S; Wex, B; Risko, C; Khnayzer, RS; Barlow, S; Patra, D; Timofeeva, T; List, EJW; Bredas, JL; Marder, SR, Journal of Materials Chemistry C, 1, 1638-1650 [2013]
  • Structural Dependence of the Optical Properties of Narrow Bandgap Semiconductors with Orthogonal Donor-Acceptor Geometries, Grimm, B; Risko, C; Azoulay, JD; Bredas, JL; Bazan, GC, Chemical Science, 4, 1807-1819 [2013]
  • Tuning the Electronic and Photophysical Properties of Heteroleptic Iridium (III) Phosphorescent Emitters through Ancillary Ligand Substitution: A Theoretical Perspective, Li, H; Winget, P; Risko, C; Sears, JS; Bredas, JL, Physical Chemistry Chemical Physics, 15, 6293-6302 [2013]
  • Materials-scale Implications of Solvent and Temperature on [6,6]-phenyl-C61-Butyric Acid Methyl Ester (PCBM): A Theoretical Perspective, Tummala, NR; Mehraeen, S; Fu, YT; Risko, C; Bredas, JL, Advanced Functional Materials, in press, [2013]
  • Charge Delocalization Through Benzene, Naphthalene and Anthracene Bridges in π-Conjugated Oligomers: An Experimental and Quantum Chemical Study, Fraind, A; Sini, G; Risko, C; Ryzhkov, LR; Bredas, JL; Tovar, JD, Journal of Physical Chemistry B, 117, 6304-6317 [2013]
  • Characterization of Charge-Carrier Transport in Semicrystalline Polymers: Electronic Couplings, Site Energies, and Charge-Carrier Dynamics in Poly(bithiophene-alt-thieothiophene) [PBTT], Poelking, C; Cho, EK; Malafeev, A; Ivanov, V; Kremer, K; Risko, C; Bredas, JL; Andrienko, D, Physical Chemistry, 117, 1633-1640 [2013]
  • Rubrene-Based Single Crystal Organic Semiconductors: Synthesis, Electronic Structure, and Charge-Transport Properties, McGarry, KA; Xie, W; Sutton, C; Risko, C; Wu, Y; Yong, VG; Bredas, JL; Frisbie, CD; Douglas, CJ, Chemistry Of Materials, 25, 2254-2263 [2013]
  • Benzo[1,2-b:6,5-b'] Dithiophene9dithiazole)-4,5-dione Derivatives: Synthesis, Electronic Properties, Crystal Packing and Charge Transport, Getmanenko, YA; Fonari, M; Risko, C; Sandhu, B; Galan, E; Zhu, L; Tongwa, P; Hwang, DK; Singh, S; Wang, H; Tiwari, SP; Loo, YL; Bredas, JL; Kippelen, B; Timofeeva, T; Marder, SR, Journal Of Materials Chemistry, 1, 1467-1481 [2013]
  • Electronic Polarization Effects upon Charge Injection in Oligoacene Molecular Crystals: Description via a Polarizable Force Field, Ryno, SM; Lee, SR; Sears, JS; Risko, C; Bredas JL, Journal Of Physical Chemistry, 117, 13853-13860 [2013]
  • Synthesis, Experimental and Theoretical Characterization, and Field-Effect Transistor Properties of A New Class of Dibenzothiophene Derivatives: From Linear to Cyclic Architectures, Qiao, Y; Wei, Z; Risko, C; Li, H.; Bredas, JL; Xu, W; Zhu, D, Journal Of Materials Chemistry, 22, 1313-1325 [2012]
  • Synthesis and Characterization of Naphthalene Diimide/Diethynylbenzene Copolymers Polymer, Sajoto, T; Tiwari,SP; Li, H; Risko, C; Barlow, S; Zhang, Q; Cho, J; Bredas, JL; Kippelen, B; Marder, SR, Polymer, 53, 1072-1078 [2012]
  • The Three-Dimensional Packing Structure and Electronic Properties of Biaxially-Oriented Poly(2,5-Bis(3-Alkylthiophene-2-yl)Thieno[3,2-b]Thiophene) Films, Cho, EK; Risko, C; Kim, D; Gysel, R; Cates Miller, N; Breiby, D; McGehee, M; Toney, M; Kline; Bredas, JL, Journal Of The American Chemical Society, 134, 6177-6190 [2012]
  • Tuning Delocalization in the Radical Cations of 1,4-Bis[4-(diarylamino)styryl]thiophenes, and 2,5-Bis[4-(diarylamino)styryl]pyrroles Through Substituent Effects, Barlow, S; Risko, C; Odom, S; Zheng, S; Coropceanu, V; Beverina, L; Bredas, JL; Marder, SR, Journal Of The American Chemical Society, 134, 10146-10155 [2012]
  • Controlled Conjugated Backbone Twisting for an Increased Open-Circuit Voltage while Having a High Short-Circuit Current in Poly(hexylthiophene) Derivatives, Ko, SW; Hoke, ET; Pandey, L; Hong, SH; Monday, R; Risko, C; Yi, Y; Noriega, R; McGehee, MD; Bredas, JL;, Journal Of The American Chemical Society, 134, 5222-5232 [2012]
  • Factors Governing Intercalation of Fullerenes and Other Small Molecules Between the Side chains of Semiconducting Polymers Used in Solar Cells, Cates Miller, N; Cho, EK; Gysel, R; Risko, C; Coropceanu, V; Miller, CE; Sweetnam, S; Sellinger, A; Heeney, M; McCulloch, I; Bredas, JL; Toney, MF; McGehee, MD, Advanced Energy Materials, 2, 1208-1217 [2012]
  • Polymethine Dyes for All-optical Swtiching Applications: A Quantum-chemical Characterization of Counter-ion and Aggregation Effects on Third-order Nonlinear Optical Response, Mukhopadhyay, S; Risko, C; Marder, SR; Bredas, JL, Chemical Science, 3, 3103-3112 [2012]
  • Synthetic Principles Directing Charge Transport in Low-Band Gap Dithienosilole-Benzothiadiazole Copolymers, Beaujuge, PM; Tsao, HN; Hansen, MR; Amb, CM; Risko, C; Subbiah, J; Choudhury, KR; Mavrinskiy, A; Pisula, W; Bredas, JL; So, F; Mullen, K; Reynolds, JR, Journal Of The American Chemical Society, 134, 8944-8957 [2012]
  • Donor-Acceptor Copolymers of Relevance for Organic Photovoltaics: A Theoretical Investigation of the Impact of Chemical Structure Modifications on the Electronic and Optical Properties, Pandey, L; Risko, C; Norton, JE; Bredas, JL, Macromolecules, 45, 6405-6414 [2012]
  • Unification of Trap-limited Electron Transport in Semiconducting Polymers, Nicolai, HT; Kruik, M; Wetzelaer, GA; de Boer, B; Campbell, C; Risko, C; Bredas, JL; Blom, PW, Nature Materials, 11, 882-887 [2012]
  • Use of X-Ray Diffraction, Molecular Simulations, and Spectroscopy to Determine the Molecular Packing in a Polymer-Fullerene Biomolecular Crystal, Miller, NC; Cho, Ek; Junk, MJN; Gysel, R; Risko, C; Kim D; Sweetnam, S; Miller, CE; Richter, LJ; Kline, RJ; Heeney, M; McCulloch, I; Zhao, K; Graham, KR; Amassian, A; Acevedo-Feliz, D; Knox, C; Ryan Hansen, M; Dudenko, D; Chmelka, BF; Toney, MF; Bredas, JL; McGehee, MD, Advanced Materials, 24, 6071-6079 [2012]
  • n-Doping of Organic Electronic Materials Using Air-Stable Organometallics: A Mechanic Study of Reduction by Dimeric Sandwich Compounds, Barlow, S; Guo, S; Mohapatra, SK; Romanov, A; Timofeeva, T; Hardcastle, KI; Kada, Y; Risko, C; Bredas, JL; and Marder, SR, Chemistry-A European Journal, 18, 14760-14772 [2012]
  • Benzo[1,2-b:6,5-b']dithiophene(dithiazole)-4,5-Dione Derivatives: Synthesis, Electronic Properties, Crystal Packing and Charge Transport, Getmanenko; Fonari, M; Risko, C; Sandhu, B; Galan, E; Zhu, L; Tongwa, P; Hwang, DK; Singh, S; Wang, H; Tiwari, SP; Loo, YL; Bredas, JL; Kippelen, B; Timofeeva, T; Marder, S, Journal of Materials Chemistry C, 1, 1467-1481 [2012]
  • A Quantum-Chemical Perspective Into Low Optical-Gap Polymers for Highly-Efficient Organic Solar Cells, Risko, C; McGehee, MD; Bredas, JL, Chemical Science, 2, 1200-1218 [2011]
  • Mono and Dicarbonyl-Bridged Tricyclic Heterocyclic Acceptors: Synthesis and Electronic Properties, Getmanenko, Y; Risko, C; Tongway, P; Kim, EG; Li, H; Sandhu, B; Tmofeeva, T; Bredas, JL; Marder, SR, Journal of Organic Chemistry, 76, 2660-2671 [2011]
  • Solution-Processed Molecular Bis(Naphthalene Diimide) Derivatives with High Electron Mobility, Polander, L; Tiwari, S; Pandey, L; Seifried, B; Zhang, Q; Barlow, S; Risko, C; Bredas, JL; Kippelen, B; Marder, SR, Chemistry Of Materials, 23, 3408-3410 [2011]
  • Benzothiadiazole-Dithienopyrole Donor-Acceptor-Donor and Acceptor-Donor-Acceptor Triads: Synthesis and Optical, Electrochemical, and Charge-Transport Properties, Polander, LE; Pandey, L; Barlow, S; Tiwari, S; Risko, C; Kippelen, B; Bredas, J; Marder, SR, Journal Of Physical Chemistry, 115, 23149-23163 [2011]
  • Solution-Processed Organic Solar Cells with Power Conversion Efficiencies of 2.5% using Benzothiadiazole/Imide-Based Acceptors, Bloking, J; Han, X; Higgs, Z; Kastrop, J; Pandey, L; Norton, J; Risko, C; Chen, C; Bredas, JL; McGehee, M; Sellinger, A, Chemistry Of Materials, 23, 5484-5490 [2011]
  • Fullerene-Carbene Lewis Acid-Base Adducts, Li, H; Risko, C; Seo, JH; Campbell, C; Wu, G; Bredas, JL; Bazan, GC, Journal Of The American Chemical Society, 133, 12410-12413 [2011]
  • Transition from Tunneling to Hopping Transport in Long, Conjugated Oligo-imine Wires Connected to Metals, Choi, SH; Risko, C; Ruiz Delgado, MC; Kim, BS; Bredas, JL; Frisbie, DC, Journal Of The American Chemical Society, 132, 4358-4368 [2010]
  • Tuning the Optoelectronic Properties of Vinylene-Linked Donor-acceptor Copolymers for Organic Photovoltaics, Ko, S; Mondal, R; Risko, C; Lee, JK; Hong, S; McGehee, MD; Bredas, JL; Bao, Z, Macromolecules, 43, 6685-6698 [2010]