Chargers for modern phones are made to accept about 90-240 Volts - which covers anywhere in the world that there's electricity, so all you'll need is a plug adapter. (Since it costs the same to make a switching charger [which is what modern ones are] with 90-240 Volts input, or with 90-120 Volts input, and it costs to make 2 different chargers, it's cheaper for the manufacturers to make a single universal charger for each phone model, and just put them into cases with plugs for the appropriate country.)