Dittrich T, Macor L, Gervaldo M, Fungo F, Otero L, Lin CY, Chi LC, Fang FC, Lii SW, Wong KT, et al. Charge separation in donor-acceptor spiro compounds at metal and metal oxide surfaces investigated by surface photovoltage. J Nanosci Nanotechnol. 2013  ;13(7):5158-63.