The effect of alkyl chains in substituted diphenylmethano[70]fullerenes (C70-DPM) on the device characteristics of DPP(TBFu)2 small molecule-based bulk heterojunction (BHJ) organic solar cell devices is investigated. By measuring charge carrier mobilities as well as the morphology and crystallinity of each device we have been able to understand and explain the differences found between solar ce...

Among the parameters that characterize a solar cell and define its power-conversion efficiency, the fill factor is the least well understood, making targeted improvements difficult. Here we quantify the competition between charge extraction and recombination by using a single parameter θ, and we demonstrate that this parameter is directly related to the fill factor of many different bulk-hetero...

Ultra violet photoelectron spectroscopy measurements in combination with the Integer Charge Transfer model is used to obtain the energy level alignment diagrams for two common types of bulk heterojunction solar cell devices based on poly(3-hexylthiophene) or poly(2-methoxy-5-(3’,7’-dimethyloctyloxy)-1,4-phenylene vinylene) as the donor polymer and (6,6)phenyl-C61-butric-acid as the acceptor mol...

To enhance the power conversion efficiency in organic solar cells, charge recombination loss needs to be minimized. First, we perform transient absorption spectroscopy to study the charge recombination dynamics of thin film bulk heterojunction of the archetype organic solar cell molecules, copper phthalocyanine (CuPC) and 3,4,9,10-perylenetetracarboxylic bis-benzimidazole (PTCBI). We report the...

The efficiency of polymer solar cells critically depends on the intimacy of mixing of the donor and acceptor semiconductors used in these devices to create charges and on the presence of unhindered percolation pathways in the individual components to transport holes and electrons. The visualization of these bulk heterojunction morphologies in three dimensions has been challenging and has hamper...

In this paper, we will present a Pc1D numerical simulation for heterojunction (HJ) silicon solar cells, and discuss their possibilities and limitations. By means of modeling and numerical computer simulation, the influence of emitter-layer/intrinsic-layer/crystalline-Si heterostructures with different thickness and crystallinity on the solar cell performance is investigated and compared with ho...

We review the application of impedance spectroscopy in dye-sensitized solar cells, quantum dot-sensitized solar cells and organic bulk heterojunction solar cells. We emphasize the interpretation of the impedance parameters for determining the internal features of the device, concerning the carrier distribution, materials properties such as the density of states and/or doping of the semiconducto...

We report on the effects of enhanced absorption/scattering from arrays of Au nanopillars of varied size and spacing on the spectral response of a P3HT:PCBM bulk heterojunction solar cell. Nanopillar array-patterned devices do show increased optical extinction within a narrow range of wavelengths compared to control samples without such arrays. The measured external quantum efficiency and calcul...

Regioregular conjugated polymers containing alternating pyridyl[2,1,3]thiadiazole (PT) and indacenodithiophene (IDT) structural units were synthesized. In these copolymers, the pyridyl nitrogen atoms on PT are precisely arranged along the backbone so that each one has an adjacent proximal and an adjacent distal counterpart across the two IDT flanking units. We find that despite the absence of o...

We report different solar cell designs which allow a simple electrical connection of subsequent devices deposited on the same substrate. By arranging the so-called standard and inverted solar cell architectures next to each other, a serial connection of the two devices can easily be realized by a single compound electrode. In this work, we tested different interfacial layer materials, such as p...