[1] H. Sasabe and J. Kido, J. Mater. Chem. C 1, 1699 (2013).

[2] T. Nakayama, K. Hiyama, K. Furukawa, and H. Ohtani, "19.1: Invited Paper: Development of Phosphorescent White OLED with Extremely High Power Efficiency and Long Lifetime" in SID Symposium Digest of Technical Papers 38, 1018 (2007).

[3] C. F. Madigan, M. H. Lu, and J. C. Sturm, Appl. Phys. Lett. 76, 1650 (2000).

[4] J. Yang, Q. Bao, Z. Xu, Y. Li, J. Tang, and S. Shen, Appl. Phys. Lett. 97, 223303 (2010).

[5] D. S. Mehta and K. Saxena, in Proceedings of Asian Society for Information Display 198 (2006).

[6] J. H. Jang, M. C. Oh, T. H. Yoon, and J. C. Kim, Appl. Phys. Lett. 97, 123302 (2010).

[7] U. Geyer, J. Hauss, B. Riedel, S. Gleiss, U. Lemmer, and M. Gerken, Appl. Phys. Lett. 104, 093111 (2008).

[8] A. Kumar, R. Strivastava, M. N. Kamalasanan, and D. S. Mahta, Opt. Lett. 37, 575 (2012).

[9] B. Wang, L. Ke, and S. J. Chua, J. Cryst. Growth 288, 199 (2006).

[10] B. K. Hong, H. K. Yu, I. Lee, K. Kim, S. Kim, and J. L. Lee, Adv. Mater. 2010, 22 (2010).

[11] A. Kumar, R. Strivastava, P. Tyagi, M. N. Kamalasanan, and D. S. Mahta, Org. Electron. 13, 2879 (2012).

[12] Q. Y. Yue, W. Li, F. M. Kong, and K. Li, Adv. Mater. Sci. Eng. 2012, 985762 (2012).

[13] M. Le, R. Yan, and Q. Wang, Semicond. Photon. Technol. 12, 10 (2006).

[14] Y. J. Lee, S. H. Kim, J. Huh, G. H. Kim, Y. H. Lee, S. H. Cho, Y. C. Kim, and Y. R. Do, Appl. Phys. Lett. 82, 3779 (2003).

[15] E. D. Palik, Handbook of Optical Constants of Solids (Academic, Orlando, 1985).

[16] A. W. Snyder and J. Love, Optical Waveguide Theory (Springer, Berlin, 1993).

[17] B. E. Little and W. P. Huang, Prog. Electromagn. Res. 10, 217 (1995).