An LED lamp comprises a lamp housing, a heat sink made of metal and mounted at a bottom side of the lamp housing, a plurality of LED modules, and a vapor chamber having a bottom surface thereof attached to a top surface of the heat sink and having a top surface thereof to which the LED modules are attached, a working liquid is sealed in the vapor chamber. The photovoltaic cell is able to have a substrate made of a composite material. An actuator is disposed on the opposite side of the cavity to the wall for vibrating the ink in the cavity by itself vibrating relative to the wall. An on-line ticketing application using the VBI is described.