The barcode library we use has not had rotation option yet but there is a CSS solution like this:

<style>
	.vertical_barcode {
		transform: rotate(-90deg);
		transform-origin: right, top;
		-ms-transform: rotate(-90deg);
		-ms-transform-origin: right, top;
		-webkit-transform: rotate(-90deg);
		-webkit-transform-origin: right, top;
	}
</style>
<div class="vertical_barcode">
	<?php
	\koolreport\barcode\BarCode::create(array(
		"format" => "html",
		"value" => "081231723897",
		"type" => "TYPE_CODE_128"
	));
	return;
	?>
</div> 

This will work for both web view and PDF cloud export, bar the normal export package which doesn't support CSS transform style.