When you call a list screen your report generates a downloadable report after execution. This report seems as a spool list if you run your program in background. There are two ways to generate a list screen. First one is using WRITE command and the second one is using REUSE_ALV_GRID_DISPLAY which serves to output internal table as an ALV list.
You have to follow a few steps to export spool list of your background job.
Go to SM37 and find your background job then hit spool list.
Find total page number of your spool list
Go to settings of your spool list
Give your total number of pages ‘To Page’ of spool list
Click ‘Save as a local copy’ button to download list as excel,html,txt to your local