Organic Photo Sensors for Detection of VUV Scintillation Light *

Liquid noble gas scintillators are widely used in rare-event physics detectors due to their low cost, high availability and excellent scintillation properties. Typically, they scintillate in the VUV range ($\sim$128 nm for LAr) with the light detected via PMTs or SiPMs. However, there are few optical sensors that can directly detect 128 nm light, so these devices often rely on wavelength shifters. As experiments pursue towards multi ton-scale detectors, these detection schemes become cost prohibitive. Recent work on the development of organic semiconductor photodiodes at ORNL provides a potential solution using low-cost organic photodiodes. Ongoing research into organic photodiodes is addressing transparent and sensor functionality in the liquid noble gas environment (such as LAr $\sim$128 nm, $\sim$ 87 K) by using specific materials that are transparent to VUV light. This talk will outline the fabrication and characterization of conductive polymer:fullerene-based organic photodiodes, with details of the performance of these photodiodes and method of fabrication also being presented.