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An analytical model of the photocurrent-voltage characteristics has been utilized to analyze important properties of organic bulk-heterojunction solar cells, e.g., generation rate, electron current density, hole current density and the total photocurrent density. The generation rate of P3HT:PCBM based solar cell critically depends on the absorption coefficient. For measuring the electron and hole current density solution of carrier continuity equation is used in MATLAB. Then the effects of electron and hole current density on the performance of P3HT solar cells have been studied. The result of this paper demonstrate that current density due to electron plays a major role in photocurrent production while hole current density has a very little impact. Effect of electron and hole mobility variation are investigated separately which indicate that increasing electron mobility are extremely important than hole mobility to increase the power conversion efficiency of P3HT:PCBM blend. The dependence of electron and hole current densities as a function of the blend thickness is also analyzed.

Tandem solar cell provides an effective way to improve power conversion efficiency of organic solar cell by combining two or more organic solar cells. Each cell has different absorption maximum and width so it provides the amenities of using the photon energy more effectively. Due to the limited absorption band of organic materials, single junction organic solar cells suffer from low efficiency. Here, we demonstrate the performance of single layer devices based on the solution of carrier continuity equation in MATLAB. Polymers P3HT:PCBM, pBBTDPP2:PCBM and PCDTBT:PCBM provide power conversion efficiency of 3%, 3.15% and 6.2% respectively. Hence series connected tandem cell P3HT:PCBM as front cell and pBBTDPP2:PCBM as rear cell is designed to achieve higher efficiency where the proposed model gives the power conversion efficiency of 6%. A major back through came when the front cell is replaced by PCDTBT:PCBM solar cell in the device configuration which provides the power conversion efficiency of 8.8%, till now the maximum efficiency for organic solar cell.