1. Materials Science and Engineering Program, Washington State University, Pullman, Washington 99164, United States
2. Department of Physics, Prince Sattam Bin Abdulaziz University, Alkharj 11942, KSA
3. Optoelectronics of Organic Semiconductors Institute, University of Potsdam, Potsdam-Golm 14476, Germany
4. Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, United States
5. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
6. Department of Mathematics, Washington State University, Pullman, Washington 99164, United States
7. Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, P. R. China
8. Department of Physics, Swansea University, Singleton Park, Swansea, Wales SA2 8PP, U.K.