Improved photovoltaic characteristics of amorphous Si thin-film solar cells containing nanostructure silver conductors fabricated using a non-vacuum process

A low-cost, highly reflective, liquid organic nanostructure silver conductor with superior conductivity, using back contact reflectors in amorphous silicon (a-Si) single-junction superstrate configuration thin-film solar cells produced using a non-vacuum screen printing process is proposed. The conductive paste is composed of Ag nanowires (Ag NWs) mixed with an Ag nanostructure (Ag NS) sheet. The paste is referred to as `Ag NWS´. A comparison of silver conductor samples with vacuum-system-sputtered silver samples indicated that the short-circuit current density (J_sc) and the open-circuit voltage (V_oc) of Ag NWS conductor cells exceeded 0.22 mA/cm² and 66 mV, respectively. The Ag NWS conductor with back contact reflectors in solar cells was analysed using external quantum efficiency measurements to effectively enhance light-trapping ability in a long wavelength region (580-700 nm). The cells constructed using the optimised Ag NWS demonstrated an increase of approximately 6.1% in power conversion efficiency under AM 1.5 illumination. These results indicated that the Ag NWS conductor back contact reflector layer is a suitable candidate for high-performance a-Si thin-film solar cells.