pdf in iframe using a folder on local host

Question

i have about 500 pdfs which have to be opened in iframe on page.i have inserted its name in database and able to retrive it.but the pblm is that i cant access that pdf when it is kept in a folder in solution explorer..

Sharing my code  

 protected void btnpdf1_Click(object sender, EventArgs e)

    {

        

        Iframe1.Attributes["src"] = @"pdf:\Aperture.pdf";

    }

here pdf is a folder in my solution explorer..but ths code doesnot work..help//

amitesh