Photoemission Studies Of Organic Semiconducting Materials Using Open Geiger-Muller Counter

We investigated an open ionization cell based on the Geiger-Muller counter principle in a gas mixture at atmospheric pressure and demonstrated that the photoemission signals as weak as 1 electron per second are detectable. This finding allowed us to investigate more accurately the photoemission spectrums, especially in the vicinity of the photoemission threshold. Using such a cell, we investigated a number of organic semiconductor materials, tested various ways to analyze the results of the measurements of photoemission spectrums, and demonstrated an efficient way to determine ionization potential by using the square root of the derivative of the yield dependence on the light quanta energy This method leads to more evident graphical representation of the measurement results and better estimation in comparison to the results estimated by using the traditional method of plotting dependence on the quanta energy h nu.