Venus - its period of rotation (day) is 243 Earth days, and its period of revolution around the sun (year) is only 225 Earth days.
But I think the question is also complicated by whether we are talking about the period of rotation (a day being the length of time for one complete rotation on its axis), or the length of time a point on the surface of the planet is actually facing the sun (ie: in daylight). For example, Mercury rotates in two thirds the time it takes to revolve, but because it rotates as it goes around the sun, the same surface actually faces the sun for a full Mercurian year.
(I don't think I have explained that well!! (And maybe not accurately) - I think I need some diagrams!!!! Anyway, forget Mercury - Venus is your answer.