Modeling and Analysis of the Effects of Surface and Interface States on the Photocurrent and the Efficiency of a Solar Cell Based on n+npp+ Structure

Abstract

In this article, we study the influence of interface and surface recombination effects on the performance of a solar cell and on the photocurrent profile. This study is applied to chalcopyrite thin film solar cell comprising 4 active layers following the model ZnO(n + )/CdS(n)/CuInS2(p)/CuInSe2(p + ) where CuInS2 represents the base and CuInSe2 the substrate. It is based on the continuity equation of charge carriers in semiconductor material and the consideration of certain optical, geometric and electrical parameters (photon absorption coefficient, diffusion length, recombination velocity at the front and the back surface and at the interface between different layers, thicknesses of the layers, etc.). We also consider monochromatic illuminations ranging from visible to near infrared. The results obtained in two-dimensional and three-dimensional representations, show that surface and interface recombination centers can dramatically reduce the efficiency of the collection of carriers for certain wavelength ranges and that the efficiency depends on the area of photon absorption. The photons generated in the depletion area or close to this area are less affected by surface defects. The losses are related to the charge carriers which cross the interfaces to reach the depletion region and those which are generated in the vicinity of the surface because of the diffusion of the latter are towards the recombination centers.

Formation, Enhanced Crystallization, Optical Absorption and Electrical Conduction in Copper Indium Selenide Thin Films Prepared via Pulse Laser Welding Technique

“…The high-low resistance ratio for these devices is larger than 5.7 and the retention times exceeded over 10 4 s. [4] Copper indium selenide thin films are prepared by various techniques including radiofrequency magnetron scattering, [5] spray pyrolysis followed by selenization process, [6] and flash evaporation techniques. [7] Each technique used for producing this material revealed different physical properties from the other.…”

“…The pulsed laser welding technique is an ultrafast technique that allows the evolution of new materials within seconds. [7][8][9] The method succeeded in producing microcrystals and microcrystalline films in a short period of time. For example, lead selenide microcrystals prepared by the pulsed laser welding technique needed only 2 min to convert Pb and Se powders into PbSe crystals.…”

“…Copper indium selenide thin films are prepared by various techniques including radiofrequency magnetron scattering, [ 5 ] spray pyrolysis followed by selenization process, [ 6 ] and flash evaporation techniques. [ 7 ] Each technique used for producing this material revealed different physical properties from the other. As for examples, thin films prepared by spin coating technique showed energy band gap values of 1.45, 1.39, and 1.58 eV, for pure and Sn and Zn doped CuInSe 2 thin films, respectively.…”

“…The novelty of the work lies in optimizing the best parameters that allow the production of this compound on large scales and short periods of time so that large film areas are produced. As we mentioned the radiofrequency magnetron scattering, [ 5 ] spray pyrolysis followed by selenization process [ 6 ] and flash evaporation techniques [ 7 ] produced CuInSe 2 thin films in longer periods of time that may extend to hours. The produced film areas are highly limited due to the long time consumption.…”