Efficient electron transfer and reduced recombination with Nd:YAG laser scribing for high-efficiency quantum dot-sensitized solar cells

Inefficient charge transfer and charge recombination are critical but challenging issues that restrict the power conversion efficiency (PCE) of quantum-dot-sensitized solar cells (QDSSCs). These issues must be addressed to boost the performance of QDSSCs. We present a novel Nd:YAG laser scribing treatment for fluorine doped tin oxide (FTO) substrate that reduces electron loss by reducing the moving distance of electrons and strongly inhibiting interfacial recombination processes in QDSSCs. Consequently, TiO2/CdS/CdSe/Mn-ZnSe QDSSCs on the Nd:YAG laser scribed FTO exhibited a PCE of 6.26% under 1 sun (100 mW cm(-2)) irradiation, while TiO2/CdS/CdSe/Mn-ZnSe QDSSCs on the FTO without Nd:YAG laser scribing exhibited a PCE of 5.51%. The short circuit current density and fill factor are also increased after laser scribing, which arises from increased electron transfer with reduced recombination. Electrochemical impedance spectroscopy modeling reveals that the Nd:YAG laser scribed QDSSC has increased charge collection efficiency and reduced interfacial recombination compared with normal QDSSC. (C) 2017 Elsevier Ltd. All rights reserved.