Flexible organic permeable base transistors are a promising transistor technology, enabling high transconductance without the need for cost-intensive structuring techniques. Here, we present a simple approach to enhance the transmission and thus the current gain of a permeable base transistor. By adding a morphology modifying gold layer beneath the organic semiconductor, the interface to the base electrode is adjusted, resulting in a self-structured permeable base. Furthermore, we show that doping is essential not only for charge injection at the emitter, but is also required at the collector for a good performance. We show that the transmission can be increased to 98% by tuning the built-in field at the collector to actively gather charge carriers. The built-in field also leads to a very low minimum operation voltage < 0.5 V, resulting in a low power consumption.