Mockup design for mobile application

Dear Graphical Designer, We are looking for talented graphical designer for doing excellent, modern design for us. We are looking for state of the art end result, so we would like to see some outstanding portfolio as well. This far we are interested about 3-4 first pages only. So, in that sense when getting right kind of "tone" and "mood" to application, it is easier to go forward with rest of the application design. We do not provide upfront payments and we only work via Freelancer, so not interested any other kind of options.