We investigate the effect of the modification of cellulose acetate propionate as an organic vehicle for silver paste on solar cell efficiency. For the modification of cellulose acetate propionate, poly(ethylene glycol) is introduced to the hydroxyl groups of a cellulose acetate propionate backbone via esterification reaction. The chemical structure and composition of poly(ethylene glycol) functionalized cellulose acetate propionate is characterized by Attenuated total reflectance Fourier transform infrared, 1H nuclear magnetic resonance, differential scanning calorimetry and thermogravimetric analysis. Due to the effect of structural change for poly(ethylene glycol) functionalized cellulose acetate propionate on the viscosity of silver paste, the solar cell efficiency increases from 18.524% to 18.652 %. In addition, when ethylene carbonate, which has a structure similar to poly(ethylene glycol), is introduced to cellulose acetate propionate via ring opening polymerization, we find that the efficiency of the solar cell increases from 18.524% to 18.622%.

In commercial solar cells, the pattern of the front electrode is critical to effectively assemble the photo generated current. The power loss in solar cells caused by the front electrode was categorized as four types. First, losses due to the metallic resistance of the electrode. Second, losses due to the contact resistance of the electrode and emitter. Third, losses due to the emitter resistance when current flows through the emitter. Fourth, losses due to the shading effect of the front metal electrode, which has a high reflectance. In this paper, optimizing the number of finger on a 4 ´ 4 solar cell is demonstrated with known theory. We compared the short circuit current density and fill factor to evaluate the power loss from the front metal contact calculation result. By experiment, the short circuit current density(Jsc), taken in each pattern as 37.61, 37.53, and 37.38 mA/ cm2 decreased as the number of fingers increased. The fill factor(FF), measured in each pattern as 0.7745, 0.7782 and 0.7843 increased as number of fingers increased. The results suggested that the efficiency(Eff) was measured in each pattern as 17.51, 17.81, and 17.84 %. Throughout this study, the short-circuit current densities(Jsc) and fill factor(FF) varied according to the number of fingers in the front metal pattern. The effects on the efficiency of the two factors were also investigated.

Light scattering enhancement is widely used to enhance the optical absorption efficiency of dye-sensitized solar cells. In this work, we systematically analyzed the effects of spherical voids distributed as light-scattering centers in photoanode films made of an assembly of zinc oxide nanoparticles. Spherical voids in electrode films were formed using a sacrificial template of polystyrene (PS) spheres. The diameter and volume concentration of these spheres was varied to optimize the efficiency of dye-sensitized solar cells. The effects of film thickness on this efficiency was also examined. Electrochemical impedance spectroscopy was performed to study electron transport in the electrodes. The highest power conversion efficiency of 4.07 % was observed with 12μm film thickness. This relatively low optimum thickness of the electrode film is due to the enhanced light absorption caused by the light scattering centers of voids distributed in the film.

용해성이 우수하며, 강한 electron-withdrawing 특성을 나타내는 cyano group 을 가지는, 새로운 전자acceptor 재료인 malononitrile 유도체 (2-(2,6-bis((E)-4-tert-butylstyryl)-4H-pyran-4-ylid-ene)malononitrile (t-BuPM)을 합성하였다. 합성된 acceptor 재료 t-BuPM을 donor와 acceptor 재료로 널리 사용되고 있는 poly[2-Methoxy-5-(2-EthylHexyloxy)-P-Phenylene-Vinylene](MEH-PPV)와 (6)-1-(3-(methoxycarbonyl)propyl)-{5}-1-1-phenyl-[5,6]-fullerene (PCBM)과 함께ternary blend system으로 유기 태양전지 소자를 제작하였다. 소자는 ITO/PEDOT:PSS/MEH-PPV:t-BuPM:PCBM/Al 구조와 같이 제작하여 광전변환 특성을 측정하였다. 합성된 재료의 HOMO와LUMO energy level은 -5.97,-3.49eV로 측정되었으며, t-BuPM을 사용하여 ternary blend system 으로 제작된소자의 에너지변환 효율은 AM 1.5G, 1 sun 조건(100mA/cm2)에서 1.85%로 측정되었다. Short circuit current density (Jsc)는 5.54mA/cm2, fillfactor(FF)는 41%, open circuit voltage(Voc)는 0.80 V로 측정되었다.