Solution-based semiconductors give rise to the next generation of thin-film electronics. Solution-based silicon as a starting material is of particular interest because of its favorable properties, which are already vastly used in conventional electronics. Here, the application of a silicon precursor based on neopentasilane for the preparation of thin-film solar cells is reported for the first time, and, for the first time, a performance similar to conventional fabrication methods is demonstrated. Because three different functional layers, n-type contact layer, intrinsic absorber, and p-type contact layer, have to be stacked on top of each other, such a device is a very demanding benchmark test of performance of solution-based semiconductors. Complete amorphous silicon n-i-p solar cells with an efficiency of 3.5% are demonstrated, which significantly exceeds previously reported values.