With the advent of medical technology multiple high power sources are employed for diagnosis and treatment. Utilisation of x-rays, NIR and UV light beams are to name a few. In particular, UV radiation between 320 to 280 nm (UV-B region) has find potentiality in skin related treatments. But these radiations has to be employed in controlled fashion as that small variation in intensity or power may leads to lethal damage. In this regard, high precision photodetectors are required to precisely monitor and signal the output variation. Like any application, inorganic materials are reported to have excellent responsivity to the applied field along with the development of commercial devices. But, the modern medical industry seeks flexible, skin friendly, wearable devices. In this regard, often organic systems are recommended due to their ease in fabrication on any substrate, tailorability to precisely tune the absorption curves and low material costs. But before developing a prototype several issues like improving the responsivity, reducing the dark current, narrow band detection has to be addressed properly. So, herewith we are proposing to fabricate and evaluate two organic semiconductor based phototransistors for the detection of UV-B radiation. So our objective is (i) To introduce dual layer architecture in an organic phototransistor to reduce dark current and improve photocurrent (ii) To optimize the device operable at low driving voltages (less than 5 V). (iii) To evaluate the two different OSCs (pentacene and tetracene) and optimizing them for narrow band detection. (iv) To demonstrate a prototype organic phototransistor in UV-B region.