Parameters critically affecting the open circuit voltage of an organic solar cell
Pelote Elvis Pepa, David Afungchui, Olivier Holtomo, Ebobenow Joseph
Abstract
This paper investigates the influence of different parameters on the open circuit voltage of an organic solar cell (OSC) and how the open circuit voltage impacts the cell's power conversion efficiency. These parameters include temperature, light intensity, recombination, charge carrier density, charge carrier mobility ratio, and the reverse saturation current. Organic solar cells' power conversion efficiency is still far from ideal and is currently about 20 %. In the approach, mathematical expressions governing these parameters are established and simulations are then performed in which all other parameters are held at their optimal values and one parameter of interest is varied within a predetermined range. It is shown that the open circuit voltage (V oc ) can theoretically reach a value of about 2.34 V if the following parameters are maintained optimal: light intensity, charge-carrier density (1 × 10 18 cm −3 ), charge carrier mobility ratio (10) and cell temperature (320 K). It is shown that the open circuit voltage (V oc ) is negatively impacted by recombination (up to 30 Ω). Lastly, the power conversion efficiency is predicted to be 20 % at 0.63 V and can reach a theoretical value of 37 % at a V oc of 1.0 V, at a power intensity input of 6.578 w/m 2 , and a fill factor of 0.89 (max for silicon).