The influence of annealing temperature and time on the efficiency of pentacene: PTCDI organic solar cells

In this study, fabrication of a polycyclic aromatic hydrocarbon/Perylene Tetracarboxylic Di-Imide (PTCDI), donor/acceptor solar cells are presented using physical vapour deposition technique in a 1000 class glove box. An ITO/PEDOT:PSS/Pentacene/PTCDI/Al (ITO=Indium Tin Oxide and PEDOT:PSS=poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) solar cell has been obtained and the power conversion efficiency, PCE (η) of about 0.33% has been obtained under simulated solar illumination of 300W/m2. Furthermore, the effects of annealing temperatures (at 100 and 150°C) and of annealing (at 100°C) times for 5 and 10min. on the power conversion efficiency, η of the solar cells have also been investigated. In general, it has been seen that the thermal annealing deteriorated the characteristics parameters of Pentacene/PTCDI solar cell such that both fill factor, FF and η decreased after annealing and with increase of annealing time. Atomic force microscopy (AFM) images showed that the phase segregation and grain size increased and the surface roughness of Pentacene film decreased and these effects reduced the η value. The η values of the solar cell have been determined as 0.33%, 0.12% and 0.06% for pre-annealing, annealing at 100 and 150°C, respectively.