Silicon solar cells have proven to be a top photovoltaic technology, as they use earth abundant raw materials (i.e. Si) and perform with high efficiency. However, they are based on thick, rigid and heavy wafers and can therefore only be installed in a limited number of places. One of the ways to overcome this disadvantage is to use thin membranes instead. This will reduce the amount of Si by more than 99% (dramatically saving in raw materials) and also make the cells flexible and lightweight. As such, these cells can be easily integrated into buildings, urban architecture and even small everyday gadgets. The problem is that such thin Si membranes cannot absorb light as efficiently. In fact, only 25% of the sunlight is absorbed and you can even see through them.