en Research Paper Research Paper <h1 style="margin-left:28px; margin-bottom:11px"><span style="font-size:11pt"><span style="line-height:200%"><span new="" roman="" style="font-family:" times=""><span style="font-weight:normal">We have modeled theoretical incident photon-to-current electricity (IPCE) action spectra of poly(3-hexylthiophene) (P3HT) and [6,6]-Phenyl C61 butyric acid methyl ester active layer bulk-heterojunction. By the two-dimensional optical model of a multilayer system based on the structure of Glass substrate / SiO₂ /ITO/ PEDOT: PSS /P3HT: PCBM(1:1)/Ca/Al, the optical responses of the device have been computed for different photoactive layer and Ca layer thicknesses to found an optimal structure which allows obtaining the maximum absorption localized in the active layer and high device performance. The electric field intensity, energy dissipation, generation rate, and IPCE have been computed to enhance the device&#39;s performance. The finite element method executes the simulation under an incident intensity of 100 mW/cm² of the 1.5 AM illumination. It was found that the optimum structure is achieved by a 180 nm photoactive layer and 5 nm Ca layer thicknesses.</span></span></span></span></h1> Organic solar cells,Optical responses,Optimal structure,Absorption,Generation rate 145 150 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-5187-1&slc_lang=en&sid=1 Fathi Brioua brioua.f@univ-adrar.edu.dz 1800319475328460019209 1800319475328460019209 Yes Département Génie Électrique, Université Ahmed Draia, Adrar, Algeria. Chouaib Daoudi ch.daoudi@univ-skikda.dz 1800319475328460019210 1800319475328460019210 No Département de Génie Électrique, Université 20 Août 1955, Skikda, Algeria.