Query: Modelling polycrystalline semiconductor solar cells

Candidate papers:

abstract: Solar cells are semiconductor devices that generate electricity through charge generation upon illumination. For optimal device efficiency, the photo generated carriers must reach the electrical contact layers before they recombine. A deep understanding of the recombination process and transport behavior is essential to design better devices. Halide perovskite solar cells are commonly made of a polycrystalline absorber layer, but there is no consensus on the nature and role of grain boundaries. This review paper concerns theoretical approaches for the investigation of extended defects. We introduce recent computational studies on grain boundaries, and their influence on point defect distributions, in halide perovskite solar cells. We conclude the paper with discussion of future research directions.
author_names: Ji-Sang Park

Aron Walsh
title: Modelling Grain Boundaries in Polycrystalline Halide Perovskite Solar Cells
year: 2020

abstract: The parallel multi junction solar cell design has recently been proposed to reduce the costs of photovoltaics, while maintaining or improving device performance. This design uses alternating layers of n and p type semiconductor to ensure that every point in the device is much less than one diffusion length from a collecting junction, producing relatively high currents. Device voltages can be maintained through heavier doping than would normally be used. This approach is particularly suited to very low quality material where the diffusion lengths are much shorter than the device thickess required for significant photogeneration. In particular, this design strategy is seen as a way to realize the potential of thin film polycrystalline silicon solar cells for large scale, cost effective energy generation. A brief description of the parallel multi junction solar cell is presented, along with some analysis where parallel multi junction solar cells differ from conventional cells. Results from an analytical one dimensional model and two dimensional numerical simulations are presented, highlighting some of the significant advantages of parallel multi junction solar cells.
author_names: S Edmiston

Alistair B Sproul

Martin A Green

S R Wenham
title: Modelling of Thin film Crystalline Silicon Parallel Multi junction Solar Cells
year: 1995

abstract: A two dimensional (2D) analytical model based on the Green's Function method is applied to an n p thin film polycrystalline solar cell that allows us to calculate the conversion efficiency. This model considers the effective Gaussian doping profile in the p region in order to improve cell efficiency. The dependence of mobility and lifetime on grain doping is also investigated. This model is implemented through a simulation program in order to optimize conversion efficiency while varying thickness and doping profile in the base region of the cell. Compared with n p standard structure, our proposed structure shows a 43% improvement in conversion efficiency for a polycrystalline solar cell. PACS. 85.30.De Semiconductor device, characterization, design and modelling. 88.40.hj Efficiency and performance of solar cells.
author_names: Sami Kolsi

Mohamed Ben Amar

Hekmet Samet

A Ouali
title: Effect of Gaussian doping profile on the performance of a thin film polycrystalline solar cell
year: 2012

abstract: Abstract The "classical" Volger Petritz Berger barrier model of the thin polycrystalline layer is developed, thereby enabling a coherent mathematical description of this model in stationary conditions to be given. The symmetric and asymmetric barriers as well as the effect of the thickness of the grain boundary region on the height of the potential barrier (the diffusion barrier) are analysed. The model presented is based on abrupt low high type semiconductor structures and is complementary to and a development of theoretical models with Schottky barriers, p n junctions, heterojunctions or trapping. The development of the trapping model, which is the most advanced model theoretically and which is particularly useful for polycrystalline layers of elemental semiconductors, is outlined. The literature quoted enables the results obtained with both models to be compared. The present results are applicable in analyses of the electrical properties of polycrystalline solar cells.
author_names: Zbigniew T Kuznicki
title: Modelling of semiconductor polycrystalline layers in the stationary state
year: 1984

abstract: Abstract Chemical bath deposition (CBD) generates has been successfully employed for the fabrication of II VI semiconductor thin films. Thin film polycrystalline solar cells, such as the BP Solar 'Apollo' CdS:CdTe heterojunction device, offer the potential for low cost solar energy conversion. The large scale exploitation of these devices is partly dependent on a reduction of the potential environmental impact of the technology. The fabrication of CdS window layers by CBD at present generates considerable Cd containing waste. Use and disposal of cadmium containing compounds and wastes are highly regulated in the EU and elsewhere. For CdS CBD, the extent of the desired heterogeneous reaction on the substrate surface is limited by two major factors, the competing homogeneous reaction in solution and deposition of material on the CBD reactor walls. In this paper we describe our initial successful efforts to address these problems with the development of a novel high efficiency CdS CBD system. Chemical modelling and speciation studies have enabled us to develop a process that comprises low cadmium concentrations and eliminates ammonia (which is volatile and undesirable for large scale CBD operations) Films have been characterised by spectroscopic methods (UV vis, PL and XPS) microscopy (SEM and TEM) and powder XRD.
author_names: David S Boyle

Alexander Bayer

Markus R Heinrich

Odile Robbe

Paul O'Brien
title: Novel approach to the chemical bath deposition of chalcogenide semiconductors
year: 2000

abstract: Although this is the 16th volume in a long standing and successful series, the focus is no longer limited to hydrogenated amorphous silicon (a Si:H) The distinction between short and medium range order, and between homogeneous and heterogeneous semiconductor materials, is indeed too difficult to maintain. Instead, the volume covers amorphous and microcrystalline silicon from materials physics to new applications. Papers from a joint session with a symposium on Flat Panel Display Materials and Large Area Processes are included. The volume also features special focused sessions on heterogeneous materials, color sensors and radiation imaging, and parameter extraction and device modelling. Topics include: amorphous and polycrystalline thin film transistors; solar cells; color and X ray sensors, novel devices, luminescence and sensitization; device modelling and parameter extraction; growth, alloys and clathrates; metastability, hydrogen, atomic and electronic structure; defects and charge transport; and heterogeneous silicon formation, properties and devices.
author_names: Ruud E I Schropp
title: Amorphous and microcrystalline silicon technology 1998 symposium held April 14 17, 1998, San Francisco, California, U.S.A.
year: 1999

abstract: Abstract An overview is given of various electronic effects present in polycrystalline thin film solar cells, which do not occur in standard crystalline Si solar cells. It is explained how these effects are treated numerically in a numerical solar cell simulation tool, SCAPS, developed at the author's institute. The capabilities and limitations of SCAPS are discussed. Simulation examples of current voltage, capacitance voltage and capacitance frequency characteristics are given. The agreement between the simulations and measurements is shown and discussed, both for CdTe and for Cu(In,Ga)Se 2 solar cells.
author_names: Marc Burgelman

Peter Nollet

Stefaan Degrave
title: Modeling polycrystalline semiconductor solar cells
year: 1999

abstract: A model has been developed to characterize the photovoltaic properties of a thin film polycrystalline semiconductor solar cell with a metal insulator semiconductor (MIS) structure and an accumulated back contact which forms a back surface field. Semiconductor doping density, thickness, grain size, and grain boundary trap density are the parameters used to characterize the semiconductor. Collection velocity, diode ideality factor, effective junction barrier height, and light transmittance are the parameters used to characterize the MIS interfacial region. The three dimensional grain size and grain boundary problem is simplified by transforming it to an equivalent one dimensional single level bulk trap problem. The majority carrier density and the built in potential are assumed to be affected by light intensity, doping and trap densities. The effects of deep level grain boundary traps and of surface passivation on the short circuit current, open circuit voltage, fill factor, collection and conversion efficiencies of these cells are calculated based on the potential distribution in the thin film semiconductor. Recombination current and series and shunt resistance are not included and the superposition principle is not used in the calculation. Sample calculations are included for the specific case of electrodeposited n type CdTe MIS solar cells. Methods to improve the conversion efficiency and the application of modeling are discussed.
author_names: S M So

Peter V Meyers

C H Liu
title: Modeling of grain boundary effects on photovoltaic properties of metal insulator thin film polycrystalline semiconductor solar cells
venue: IEEE Transactions on Electron Devices
year: 1984

abstract: Computational models can provide significant insight into the operation mechanisms and deficiencies of photovoltaic solar cells. Solcore is a modular set of computational tools, written in Python 3, for the design and simulation of photovoltaic solar cells. Calculations can be performed on ideal, thermodynamic limiting behaviour, through to fitting experimentally accessible parameters such as dark and light IV curves and luminescence. Uniquely, it combines a complete semiconductor solver capable of modelling the optical and electrical properties of a wide range of solar cells, from quantum well devices to multi junction solar cells. The model is a multi scale simulation accounting for nanoscale phenomena such as the quantum confinement effects of semiconductor nanostructures, to micron level propagation of light through to the overall performance of solar arrays, including the modelling of the spectral irradiance based on atmospheric conditions. In this article, we summarize the capabilities in addition to providing the physical insight and mathematical formulation behind the software with the purpose of serving as both a research and teaching tool.
author_names: Diego Alonso-Alvarez

Tom Wilson

Phoebe M Pearce

Markus Fuhrer

Daniel J Farrell

Nicholas J Ekins-Daukes
title: Solcore: a multi scale, Python based library for modelling solar cells and semiconductor materials
year: 2018

abstract: Abstract A theoretical approach based on the Matthiessen rule for scattering lifetime is presented to formulate the effective characteristics of polycrystalline solar cells. Application of this method to Perovskite solar cells obtains polycrystalline bulk defect density for diverse grain sizes along with the determination of surface recombination velocity at grain boundaries. Unlike previous works on Silicon based solar cells that use an independently weighted average equation for extracting mobility, we introduce a variation of Drude Smith model for calculating the mobility from carrier lifetime and defect density. In agreement with the experiments, introduced method reveals sub picosecond background scattering times associated with phonon lattice vibrations. Obtained carrier diffusion length spans over multi micron to multi millimeter scale for grain sizes ranging from 100 nm to 1 mm. Calculated monomolecular recombination lifetimes explains elevated Photoluminescence Yield and peak position in larger grain sizes. Presented method is verified by feeding extracted parameters into Drift Diffusion equations and fitting with reported experimental photovoltaic conversion efficiency data. Finally, through employing a Gaussian distribution for grain sizes, we also study the reduction of device efficiency caused by non uniform grain size distribution as a more realistic case.
author_names: Babak Olyaeefar

Sohrab Ahmadi-kandjani

Asghar Asgari
title: Classical modelling of grain size and boundary effects in polycrystalline perovskite solar cells
year: 2018