Measurements of Efficiency Losses in Blend and Bilayer-Type Zinc Phthalocyanine/C₆₀ High-Vacuum-Processed Organic Solar Cells

Abstract

Losses of charge carriers, due to the interfacial charge recombination processes, in small molecule organic solar cells (SMOSCs) have been investigated under operating conditions. The devices consist of zinc phthalocyanine (ZnPc) as electron donor material and C60 as electron acceptor. The results obtained by using time-resolved techniques such as charge extraction (CE) and photoinduced transient photovoltage (TPV) have been compared to the measurements carried out with impedance spectroscopy (IS) and show good agreement. Significantly, much difference is observed in either the charge density distribution versus the device voltage or the charge carriers lifetime when comparing bulk heterojunction versus bilayer-type ZnPc:C60 devices. The implications of the faster charge carrier recombination with the device fill factor (FF) and the open circuit voltage (V OC) are discussed.

The Effect of Gradual Fluorination on the Properties of FnZnPc Thin Films and FnZnPc/C60 Bilayer Photovoltaic Cells

“…In this regard, a power conversion effi ciency η of 0.81% has been determined for our ZnPc/C 60 bilayer reference cells, which matches previously published data. [ 32 ] As a result of the individually improved solar cell parameters, the highest η of 1.4% is achieved for the F 4 ZnPc/C 60 OPVCs. In contrast, further fl uorination yields a decrease in η to 0.19% and 0.14% for the F 8 ZnPc/C 60 and F 16 ZnPc/C 60 bilayer devices, respectively.…”

Indoline as electron donor unit in “Push–Pull” organic small molecules for solution processed organic solar cells: Effect of the molecular π-bridge on device efficiency

“…device loss mechanisms. On the other hand, the promise 50 to obtain an efficient, non-toxic and cheaper technology 51 for solar-to-energy conversion moves forward the search 52 and design of new materials and device architectures 53 [11 -16]. 54 Current record efficiency, for single junction solution 55 processed devices made using individual light absorber 56 polymers, is close to 10%.…”

High photo-current in solution processed organic solar cells based on a porphyrin core A-π-D-π-A as electron donor material

“…Finally, the carrier losses were evaluated by measuring the interfacial carrier recombination kinetics as reported previously. [33,34,[41][42][43][44][45][46][47][48] The charge extraction of 1a-b is depicted in Figure 6a and was determined by subtracting the contribution of the geometrical capacitance. The total extracted charges are shown in the Supporting Information ( Figure S20), where the geometric contribution is indicated by a straight line and the calculated values are 80 and 64 nF cm -2 for 1a and 1b, respectively.…”