Optical characteristics of a multilayer photovoltaic cell for oblique incidence of light (original) (raw)
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Journal of Applied Physics, 2011
A transmission line model for the calculation of optical interference phenomena in dielectric multilayered structures is adopted as an alternative option to the transfer matrix model (TMM). The method is based on the transmission line theory and is exact, easy to implement and uses closed iterative forms instead of the TMMs matrix formalism. The proposed model has been appropriately modified and then applied for performance evaluation of a typical organic photovoltaic device under inclined illumination. Optical field distribution, short-circuit photocurrent and reflectivity have been calculated under different angles of light incidence. The theoretical simulations have been discussed and compared with experimental photocurrent measurements, while the influence of the photoactive layer thickness on the device efficiency has been evaluated for different angles of light incidence, taking into account its extinction coefficient anisotropy.
AIP Advances, 2017
We analyze the performance of bulk heterojunction organic solar cells under oblique incidence of light. In this regard, we present an optoelectronic analytical model that describes the current-voltage characteristics of bulk heterojunction organic solar cells taking into account the effect of angle of incidence. A closed-form general expression is derived for the optical generation rate under oblique incidence employing transfer matrix formalism. The resulting expression is then incorporated in the classical drift-diffusion transport and continuity equations of charge carriers to derive a unified expression of voltage dependent current density combining optical and electrical parameters. Thus, the model is capable of determining the accurate optical absorption in the active layer for varying angles of incidence as well as predicting the corresponding wavelength dependent external quantum efficiency of the device. The results are verified by comparing with published numerical and experimental results. We show that the maximum efficiency might be achieved at an oblique angle of incidence rather than normal incidence for certain active layer thicknesses. We also report the optimum angles at which the maximum efficiency occurs and show that they are active layer thickness dependent.
Global Journal of Pure and Applied Sciences, 2013
A theoretical study of a 3-D modelled bilayer heterojunction organic photovoltaic cell based on copper phthalocyanine (CuPc) as electron donor and fullerene (C 60 ) as electron acceptor is reported. The thin film multilayer stacking theory is applied to the bilayer heterojunction organic solar cell, with the optical matrix of the Abeles theory leading to new expression of generation rate and density of exciton photogenerated in the organic photoactive layer of CuPc/C 60 . The excitons density is investigated considering the excitons dissociation parameters at the different interfaces of the organic photoactive region, i.e. the exciton dissociation velocities S dp , S dg , S dj and S dn respectively associated to the transparent anode (ITO: Indium thin oxide)/donor (CuPc), the donor (CuPc)/acceptor (C 60 ) and the acceptor (C 60 )/metallic cathode (Al: aluminium) interfaces. Moreover, the influences of the monochromatic light wavelength λ and the thickness w of the organic photoactive layer (CuPc/C 60 ) on the exciton density are emphasized.
Materials Today: Proceedings, 2021
Organic photovoltaic is an emerging technology employing organic molecules as absorbers has gained tremendous attention in the past two decades due to its potential utilization as a renewable energy source. Contrary to conventional solar cells, excitons are formed under illumination which diffuse towards the heterojunction interface for dissociation into the photo charge-carriers. Heterojunction in the organic photovoltaic devices are formed either by stacking the layers of donor and acceptor molecules or by blending the both. Due to weak van-der Waals interaction between the molecules, intermixed states, in addition to the pure states of donor and acceptor molecules, are formed at the heterojunction interface which affects the electronic process and the power conversion efficiency. Significant efforts have been made to understand the photovoltaic process particularly in the bulk heterojunction solar cells however, least efforts have been devoted to investigate the governing mechanisms in the planner heterojunction solar cells. The motive of this study is to characterize the planar heterojunction solar cells based on the Copper Phthalocyanine (CuPc) and Fullerene (C 60) molecules under light illumination. The devices were fabricated under controlled condition in the normal device configuration, ITO (150 nm) |PEDOT:PSS (50 nm)|CuPc(20 nm)|C 60 (40 nm)|BCP(10 nm)| Ag(80 nm), and characterized performing the light intensity dependent measurement in the wide illumination range. The solar cell parameters such as open circuit voltage, short circuit current and the power conversion efficiency have been discussed as a function of illumination intensity in the wider illumination range.
Optical modeling and optimization of multilayer organic photovoltaic cells
Journal of Applied Spectroscopy
We show that the spectral position of the maxima in the exciton generation rate G in a photovoltaic cell, taking into account the spectral energy distribution in the AM1.5G solar spectrum, is determined by the absorption bands of its donor and acceptor materials. It varies slightly as the thicknesses of the layers in the cell change. Interference of light affects only the magnitude of these maxima. For a cell based on a CuPc (copper phthalocyanine)-C 60 (fullerene) heterojunction, the G maxima are located at 640 nm, 720 nm (absorption in CuPc) and close to 495 nm (absorption in C 60). The photovoltaic cell can be optimized using the ratio of the magnitudes of these maxima and their variations as layer thicknesses are varied and the exciton diffusion length is taken into account.
Spatial distribution of light absorption in organic photovoltaic devices
Solar Energy, 2005
In this paper we present methods for the optimization of light absorption of organic photoelectric bilayer devices like organic photodetectors and organic solar cells, which show the best performance if it is ensured that the spatial density of the absorbed light energy reaches its maximum in certain ''active'' areas. Mathematical simulations show interesting spatial distributions of light absorption depending on the thicknesses and the optical constants of the individual device layers. Our methods permit to dispose the maxima of absorption density to the area near the interface between the active layers of the bilayer device. We built photovoltaic devices according to the simulated configurations and gained improvements of the power conversion efficiencies of more than one magnitude. Parametric studies were carried out, which give us a suggestion for the potential active materials. Furthermore we analyzed the correlation between the photocurrent and the absorption density in given areas around the p-n junction, which will lead to better understanding of the diffusion range of dissociated charge carriers.
Energy Harvesting and Systems, 2019
Organic solar cells deal with small organic molecules for absorption of light at low cost and high efficiency. In this paper, we have analyzed the photovoltaic (PV) characteristics of double heterojunction solar cell that consists of copper phthalocyanine (CuPc) and 3,4,9,10-perylenetetracarboxylic bis-benzimidazole (PTCBI) thin films. Here, CuPc and PTCBI layers are combined by an interfacial layer consisting of nanoscale dots. Different plasmonic materials (i. e. Ag, Au, and graphene) are selected as alternative nanoscale dot layer to examine their effect on solar cell performance. Further, the solar cell performance is also examined via variation in active layer thickness. The choice of interfacial layer material and variation in active layer thickness offer grounds for future efficient PV cells.
Solar Energy Materials and Solar Cells, 2010
The detailed electrical-optical simulator ASDMP is used to model the measured output characteristics of Heterojunction with Intrinsic Thin layers "HIT" cells on P-and N-type c-Si substrates. The parameters extracted from modeling are used to understand the relative performances of the two types of HIT structures, with particular emphasis on the defect states on the surface of the c-Si wafer (N ss ), the minority carrier lifetime in the c-Si absorber, the recombination speeds at the contacts and the band discontinuities at the amorphous/crystalline interface. Except where the band discontinuities are varied, we apportion one-third of the band offset to the conduction band and two-thirds to the valence band. We find that N ss on the front surface (facing the incoming light) of the P-c-Si wafer strongly influence V oc , while those on the rear face reduce mainly the current and FF in P-c-Si HIT cells. In N-c-Si HIT cells, N ss has less influence. The lifetime of the minority carriers in the c-Si wafer, also has some influence on cell performance. However, the surface recombination speeds (SRS) of the contacts have little influence down to 10 3 cm/sec, except for the SRS of the holes at the contact that is the holecollector. The amorphous/crystalline (a-c) valence band offset is influential in all cases; and in particular leads to S-shaped characteristics in N-c-Si HIT, except when this offset is reduced by a lower P-a-Si:H band gap or tunneling of holes takes place. Finally unlike N-type HIT, the transition from front to double HIT on P-c-Si, does not appreciably improve solar cell output.
MRS Proceedings, 2009
A two-dimensional finite element simulation model for the bi-layer heterostructure organic photovoltaic (PV) cell, based on copper phthalocyanine (CuPc) and fullerene (C60) in the presence and absence of electron transport layers (ETLs) is presented. The effect of bathocuproine (BCP), tris(8-hydroxyquinolinato)aluminum (Alq3), and copper phthalocyanine (CuPc) as ETLs on short-circuit current (Jsc), open-circuit voltage (Voc), and power conversion efficiency (PCE) is investigated. The Frenkel-Poole mobility model was employed in describing the conduction mechanisms in the active layers. Singlet exciton and Langevin recombination techniques were employed to describe excitonic generation and recombination, respectively. The obtained simulation results demonstrate that the efficiency of PV cells is primarily dependent on the short-circuit current, the absorption capability of the active layers, and the charge collection efficiency at the electrodes. In addition, significant reduction in...