Not able to change TextField Border Color

I am trying to change color of the border of my TextField using a BorderSide, but it does not work.

This is my code below.

new TextField(
  decoration: new InputDecoration(
    border: new OutlineInputBorder(
      borderSide: new BorderSide(color: Colors.teal)
    ),
    hintText: 'Tell us about yourself',
    helperText: 'Keep it short, this is just a demo.',
    labelText: 'Life story',
    prefixIcon: const Icon(Icons.person, color: Colors.green,),
    prefixText: ' ',
    suffixText: 'USD',
    suffixStyle: const TextStyle(color: Colors.green)),
  )
)

Screenshot of the result is shown below.

That is not changing due to the default theme set to the screen.

So just change them for the widget you are drawing by wrapping your TextField with new ThemeData()

child: new Theme(
  data: new ThemeData(
    primaryColor: Colors.redAccent,
    primaryColorDark: Colors.red,
  ),
  child: new TextField(
    decoration: new InputDecoration(
      border: new OutlineInputBorder(
        borderSide: new BorderSide(color: Colors.teal)
      ),
      hintText: 'Tell us about yourself',
      helperText: 'Keep it short, this is just a demo.',
      labelText: 'Life story',
      prefixIcon: const Icon(
        Icons.person,
        color: Colors.green,
      ),
      prefixText: ' ',
      suffixText: 'USD',
      suffixStyle: const TextStyle(color: Colors.green)
    ),
  ),
));