The abundance of natural sugars in overripe bananas is the secret to big flavor and serious moisture in baked goods. Yellow bananas don't have as much sweet flavor and will remain starchy even after baking. If you have no "ripened' bananas, try the following:
Before peeling and mashing, put them on a baking sheet and bake in oven for 15 minutes. The skins will turn black but the flesh will turn brown, soft, and sweet.
For more banana flavor, you need to reduce the liquid from the bananas. Do this by zapping your bananas in the microwave, then draining the liquid from the fruit. Reduce the liquid down to about a quarter of the original measurement by simmering in small pan. Now measure 1 1/2 cups of the banana and the reduced liquid and add to recipe. This gives the bread an intense fruity banana flavor.