![]() Limitations in determining a value for the mobility of the slow carrier include not knowing the relative permittivity, and not knowing the absolute generation rate. The near square root dependence of photocurrent density with voltage and close to three-quarter power dependence on incident light intensity lead us to believe that these devices exhibit characteristics of space-charge-limited photocurrent as described by Eq. The effect of extraction and injection barriers on the shape of the J-V response and V oc has been discussed in the literature. The elimination of the kink suggests improved electrical characteristics at the interface with the electrode and the removal of an extraction barrier. The improved performance is attributed to a reorganization of the blended donor and acceptor moieties in the active layer brought about by the annealing process. Annealing the active layer film (180 ☌, 10 min) prior to the deposition of the Al cathode eliminated the kink and improved performance: J sc = 4.9 mA/cm 2 V oc = 0.75 V FF = 35% and PCE = 1.3%. Characteristic device parameters include: short-circuit current (J sc) = 3.8 mA/cm 2 open-circuit voltage (V oc) = 0.62 V fill factor (FF) = 24% and power conversion efficiency (PCE) = 0.35%. ![]() 11 A kink in the fourth quadrant of the J-V curve can be seen in Fig. ![]() Bulk heterojunction organic solar cells having a device structure of ITO/PEDOT:PSS/poly: -Phenyl C71-butyric acid methyl ester (1:4)/Al were fabricated as previously described. ![]()
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