Csv files are not get generating in var folder

I want to generate a csv file in var folder. I used these lines of code it’s not working. Can someone help me to figure it out

public function execute()
{
    $filepath = 'export/customerlist.csv';
    $this->directory->create('export');
    $stream = $this->directory->openFile($filepath, 'w+');
    $stream->lock();

    $header = ['Id', 'Name', 'Email'];
    $stream->writeCsv($header);

    $collection = $this->customerFactory->create()->getCollection();
    foreach ($collection as $customer) {
        $data = [];
        $data[] = $customer->getId();
        $data[] = $customer->getName();
        $data[] = $customer->getEmail();
        $stream->writeCsv($data);
    }
}

}