This Worked for me. You can try this
PrintDocument document = new PrintDocument();
        PrintDialog dialog = new PrintDialog();
        PrintPreviewDialog printPreviewDialog1 = new PrintPreviewDialog();
        private  Font printFont;
        private string stringToPrint;
      //  private int linesPerPage=9;
        private Font printFont1;
        QRCode qrCode1;
        private string stringToPrint1;
        private string databasePath;
        int i=1;
        public Form1()
        {
            InitializeComponent();
            //document.DefaultPageSettings.PrinterSettings.PrinterName = "GODEX500";
            //  document.DefaultPageSettings.Landscape = true;
            document.DefaultPageSettings.PaperSize = new PaperSize("75 x50 mm", 300, 200);
            document.DefaultPageSettings.Margins = new Margins(1, 1, 1, 1);
            printFont = new Font("Arial", 10);
            // printFont1 = new Font("NewBarcodeFont", 12);
            //    document= new Font("GODEX-NewBarcodeFont", 12, FontStyle.Regular);
            // document.OriginAtMargins = true;
            //This PrintController worked fine and not showing printing this document using window
            PrintController printController = new StandardPrintController();
            document.PrintController = printController;
            document.PrintPage += new PrintPageEventHandler(document_PrintPage);
        }