Not that is applicable to POET stock at this point in time, but anyway. Foreign stocks generating dividends are subject of witholding tax. RRSP accounts are exempt, but TFSA does not fall under that category, so if your foreign TFSA stock pays dividends you still have to pay that tax.

http://www.theglobeandmail.com/globe-investor/personal-finance/financial-road-map/foreign-dividend-withholding-tax-and-your-tfsa/article10767173/