Microcavity-like exciton-polaritons can be the primary photoexcitation in bare organic semiconductors by Pandya, R, Chen, RYS, Gu, Q, Sung, J, Schnedermann, C, Ojambati, OS, Chikkaraddy, R, Gorman, J, Jacucci, G, Onelli, OD, Willhammar, T, Johnstone, DN, Collins, SM, Midgley, PA, Auras, F, Baikie, T, Jayaprakash, R, Mathevet, F, Soucek, R, Du, M, Alvertis, AM, Ashoka, A, Vignolini, S, Lidzey, DG, Baumberg, JJ, Friend, RH, Barisien, T, Legrand, L, Chin, AW, Yuen-Zhou, J, Saikin, SK, Kukura, P, Musser, AJ, Rao, A