$site=get-spsite http://sp/sites/Echo  // the specific site URL

$ct = @()

foreach($Web in $site.AllWebs)
    {
        foreach($list in $Web.Lists)
        {
            if($list.BaseTemplate -eq "DocumentLibrary" -and $list.AllowContentTypes -eq $true)  // All Document Libraries           
            {
		foreach ($listItem in $list.Items)
		{				
			$filetype=$listItem["Type"]
				if($filetype -eq "xlsx")
				{
	    			$ctObject = New-Object -TypeName PSObject
            			// list files properties
            			$ctObject | Add-Member -Name 'WebUrl' -MemberType Noteproperty -Value $web.URL
            			$ctObject | Add-Member -Name 'ListTitle' -MemberType Noteproperty -Value $list.Title                 
            			$ctObject | Add-Member -Name 'FileUrl' -MemberType Noteproperty -Value $listItem.URL
	    		        $ctObject | Add-Member -Name 'FileName' -MemberType Noteproperty -Value $listItem.name
            		        $ctObject | Add-Member -Name 'CreatedTime' -MemberType Noteproperty -Value $listItem["Created"]
            		        $ct += $ctObject 					
	                        }
		}
			
	     }
	}
     }
		 
$ct | export-csv "C:\report1.csv"  // the Report location