In-Depth Analysis of Organic Solar Cells Using Transport Equation and Optical Transfer Matrix Method with Detailed Analytical Derivations

Abstract

Thin-film organic solar cell (OSC) performances have been investigated in detail by improved analytical computation in this work. The generation of excitons inside OSC has been estimated by using the optical transfer matrix method (OTMM) to include the optical phenomena of the incident light. The dissociation of these excitons into free charge carriers has been investigated to find the most appropriate one. OSC performances have been evaluated by an improved analytical solution of electrical transport equations including (i) exciton generation obtained from OTMM, (ii) dissociation probability incorporating Gaussian distribution to account for the natural fact of the difference in photon-energy producing excitons, (iii) recombination of charge carriers, all together. OSC properties such as JSC, VOC, FF, PCE, Pmax, absorbance, and quantum efficiency have been investigated with the variation of different parameters; this might be useful to improve OSC. Again, the presented detailed derivations of analytical expressions would be helpful for clear understanding.

Investigation of the Current of P3HT: PCBM-Based Organic Solar Cell Extracting the Spatial Recombination Coefficient of the Active Layer

“…Now, let us look at a short description of OTMM and the analytical equation derived from OTMM for calculating the generated excitons. The details of OTMM have been described in a previous report [31].…”

“…Each matrix , ′ , ′′ may be used to relate optical electric fields at its two sides, after algebraic manipulation of these relations, at any position ( ) inside active layer, the optical electric field ( ) may be determined; the square of the magnitude of ( ) is as follows [31].…”

“…Where Irradiance ( ) is the power per unit area (unit: Wm -2 or Js -1 m -2 ). We know [31] that the irradiance equation is = (1 2 ⁄ ) 2 ; for incident irradiance, 0 = (1 2 ⁄ ) 0 0 | 0 + | 2 . Now, the Eq.…”

“…between the refractive index ( ) and electric permittivity ( ), the final form of ( ) can be obtained as follows [31]:…”

“…If we multiply irradiance ( ) [unit: Js -1 m -2 ] with absorption coefficient [unit: m -1 ] and then divide by photon energy (ℎ ⁄ ) [unit: J], we can obtain the photon incident rate [unit: s -1 m -3 ]. Assuming that each photon produces each exciton, we can obtain the exciton generation rate using the following equation [31]:…”