Organic solar cells device physics

Whilst organic solar cell device models may be intended ultimately to help design the most efficient solar cells [206-210], they have proved very useful in exploring fundamental mechanisms [177, 211-214] and in helping to interpret experimental data [47, 50, 54, 58, 74, 88, 215-219]. In the following we will present a series of case studies where simulations of experimental results have allowed us to interpret experimental data better and to understand fundamental physical phenomena. Please see Appendix 3 for a short description of the used software. 

Fig. 16 Parameters for defining the charge-transfer state energy cx in organic solar cells. Charge-transfer state energy for MDMO-PPV PCBM blend device determined by Fourier transform photocurrent spectroscopy and electroluminescence measurements. Reprinted figure with permission from [188]. Copyright 2010 by the American Physical Society...

Functionalized PTs have been investigated in various applications, e.g., their ability to detect, transduce, and amplify various physical or chemical informations into an electrical or an optical signal has led to the development of devices capable of detecting analytes or biomolecules in the field of environment, security, and biotechnology. Currently, functionalized PTs play a key role as active materials in the development of electrochromic devices and electronic devices, such as OLEDs, OFETs, and organic solar cells. 

Hou J, Guo X (2013) Active layer materials for organic solar cells. Materials and device physics. In Choy WCH (ed) organic solar cells. Springer, London, pp 17-42... 

Abstract We review the methods used to simulate the optoelectronic response of organic solar cells and focus on the application of one-dimensional drift-diffusion simulations. We discuss how the important physical processes are treated and review some of the experiments necessary to determine the input parameters for device simulations. To illustrate the usefulness of drift-diffusion simulations, we discuss several case studies, addressing the influence of charged defects on transport in bipolar and unipolar devices, the influence of defects on recombination, device performance and ideality factors. To illustrate frequency domain simulations, we show how to determine the validity range of Mott-Schottky plots for thin devices. Finally, we discuss an example where optical simulations are used to calculate the parasitic absorption in contact layers. 

CurrentAoltage curves are the most important characterization technique for any solar cell technology, because they define the power conversion efficiency of the device. However, despite the simplicity of the measurement, currentA oltage curves are challenging to interpret. This is because they are rather featureless and depend on a variety of different physical phenomena. Thus, currentAoltage curves usually represent the start but rarely also the end of any investigation of the device physics of organic solar cells. 

C. H. Duan, C. M. Zhong, F. Huang and Y. Cao, Interface Engineering for High Performance Bulk-Heterojunction Polymeric Solar Cells, in Organic Solar Cells Materials and Device Physics, ed. W.C.H. Choy, Springer, 2013, pp. 43-79. 

A. Elschner and S. Kirchmeyer. 2008. PEDOT-type materials in organic solar cells. In Organic Photovoltaics Materials, Device Physics, and Manufacturing Technologies, ed. C. Brabec, V. Dyakonov, and U. Scherf. Weinheim WUey-VCH. 

In this section, we review the basic device physics of organic donor-acceptor solar cells and identify the key material and device parameters that should be addressed in order to improve power conversion efficiency. 

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