Greek letters in filename instead of full word

Question

I'm using PHPSpreadsheet to export an html table to .xlsx file. Everything works fine except...

I want to give the filename the greek fullname of the employee that is stored in a SESSION but I'm getting something like this:

2021_ΑΘΑΝΑΣΙΟΣ ΛΑΜΠΡΙΔΗΣ.xlsx

Is there a way I can set the actual name as the file name???

Edit: the code is

if(isset($_POST["file_content"]))
{
 $temporary_html_file = './tmp_html/' . time() . '.html';

 file_put_contents($temporary_html_file, $_POST["file_content"]);

 $reader = IOFactory::createReader('Html');

 $spreadsheet = $reader->load($temporary_html_file);

 $writer = IOFactory::createWriter($spreadsheet, 'Xlsx');

 $filename = $ecoYear . "_" . $_SESSION['fullname'] . '.xlsx';

 $writer->save($filename);

 header('Content-Type: application/x-www-form-urlencoded');

 header('Content-Transfer-Encoding: Binary');

 header("Content-disposition: attachment; filename=\"".$filename."\"");

 readfile($filename);

 unlink($temporary_html_file);

 unlink($filename);

 exit;
}

Answer 1

html_entity_decode — Convert HTML entities to their corresponding characters

<?php
$orig = "2021_&Alpha;&Theta;&Alpha;&Nu;&Alpha;&Sigma;&Iota;&Omicron;&Sigma; &Lambda;&Alpha;&Mu;&Pi;&Rho;&Iota;&Delta;&Eta;&Sigma;.xlsx";
$text = html_entity_decode($orig);

echo $orig . PHP_EOL;
echo $text . PHP_EOL;
?>

Output: 72103715.php

2021_ΑΘΑΝΑΣΙΟΣ ΛΑΜΠΡΙΔΗΣ.xlsx
2021_ΑΘΑΝΑΣΙΟΣ ΛΑΜΠΡΙΔΗΣ.xlsx