Error putting an object into an Array

So I'm trying to put an Object into an Array for use later and I'm getting an error every time I try. Here's my code:

 var children : GameObject[];     
 var temp : GameObject;
 
 function Start () 
 {    
     children[0] = transform.Find(this.name).Find("Teal Circle Sprite").gameObject; 
     Debug.Log("Name of object is" + children[0].name);
 }

Here's the error that I'm getting: NullReferenceException: Object reference not set to an instance of an object Dot.Start () (at Assets/Scripts/Dot.js:8)

Some more information: The name of the class is Dot and the object in question has a child called "Teal Circle Sprite"

Any help would be great! Sorry I'm kind of new at Unity!