Hole transport layers in organic solar cells : A study of work functions in nanofilms

Organic solar cells have been showing promise as a way of producing renewableenergy with the help of light, flexible, and production effective materials.The efficiencies and lifetimes reached in organic solar cells have steadily beenincreasing over the years as more research in the field is being conducted.One way of increasing the efficiency in organic solar cell devices is introducingan interlayer between the photoactive material and the anode, referred toas the ’hole transport layer’. Most commonly used as a hole transport layer isthe material PEDOT:PSS, which offers desired properties such as transparency,simple processing and good ohmic contact between anode and photoactive material.PEDOT:PSS is also known to be a degradation site in organic solar cells,as it will corrode the electrode in the presence of water.This project has consisted of investigating PEDOT:PSS along with two othercandidates that may one day come to replace PEDOT:PSS as the most commonlyused material, molybdenum trioxide (MoO3) and phosphomolybdic acid(PMA). The aim was to investigate how the different materials energy bandstructure would be affected upon exposure to sunlight, air and annealing, byobserving the work function under different conditions