Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Worksheet/Worksheet.php
public function freezePane($cell, $topLeftCell = null)
    {
        if (is_string($cell) && Coordinate::coordinateIsRange($cell)) {
            throw new Exception('Freeze pane can not be set on a range of cells.');
        }

        if ($cell !== null && $topLeftCell === null) {
            $coordinate = Coordinate::coordinateFromString($cell);
            $topLeftCell = $coordinate[0] . $coordinate[1];
        }

        $this->freezePane = $cell;
        $this->topLeftCell = $topLeftCell;

        return $this;
    }
public function freezePane($cell, $topLeftCell = null)
    {
        if (is_string($cell) && Coordinate::coordinateIsRange($cell)) {
            throw new Exception('Freeze pane can not be set on a range of cells.');
        }

        if ($cell !== null && $topLeftCell === null) {
            $coordinate = Coordinate::coordinateFromString($cell);
            $topLeftCell = $coordinate[0] . $coordinate[1];
        }

        $this->freezePane = $cell;
        $this->topLeftCell = $topLeftCell;

        return $this;
    }
Freeze Pane.

Examples:

- A2 will freeze the rows above cell A2 (i.e row 1)
- B1 will freeze the columns to the left of cell B1 (i.e column A)
- B2 will freeze the rows above and to the left of cell B2 (i.e row 1 and column A)

@param null|string $cell Position of the split
@param null|string $topLeftCell default position of the right bottom pane

@throws Exception

@return Worksheet