High efficient hybrid bulk hetero junction thin-film solar cell embedded with kesterite Cu_2ZnSnS_4 quantum dots

摘要

The photovoltaic performance of kesterite Cu_2ZnSnS_4 (CZTS) quantum dot (QD) incorporated poly(3-hexylthiophene-2,5-diyl) (Alvarado et al., 1998; Alvarado et al., 1998) [6,6]: phenyl-C61butyric acid hexyl ester (P3HT:PCBH) polymer matrix based organic hybrid heterojunction solar cell configuration is investigated. The inorganic filler material CZTS QDs with P3HT:PCBH matrix, forms double bulk hetero junction (BHJ) throughout in the active layer, which facilitates rapid exciton dissocitaion process at P3HT:PCBH and CZTS:PCBH interfaces that results effective charge carrier separation. The prepared active layer material has been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), Raman and fourier transform infra red (FTIR). The enhanced optical absorbance of prepared hybrid structure has been verified by UV-Visible analysis. It has been observed that the improvement in photo conversion efficiency (PCE) from 2.36% for the solar cell device P3HT: PCBH to 4.12% for CZTS QD based P3HT:PCBH hybrid organic solar cell device. This dramtaic increase in PCE, is mainly due to the significant enhancement in short-circuit current density (J_(sc)) from 7.6 mA/cm~2 to 11.2 mA/cm~2. That suggests, the incorporation of p-type kesterite CZTS QDs into P3HT:PCBH polymer matrix enhances the effective exciton dissociation at interfaces resulting charge separation and their fast extraction to electrodes inhibiting e~/h+ pair recombination. Furthermore, the hybrid solar cell shows remarkable time stability retaining 80% of original PCE measured after 30 days under ambient environment conditions. The hybrid organic solar cell device shows thermal stability by retaining 95.6% of its intial efficiency measured which has been tested in the temperature range 20-80 °C.