Enhancement of porous PZnO thin film using acid vapor treatment for efficient solar cells

Abstract In this work, a (porous zinc oxide) /silicon (PZnO/Si) heterojunction solar cell is prepared using a facile sol–gel/spin coating technique, followed by an acid vapor etching treatment implemented to passivate and texturize the ZnO layer. The treatment modified the surface morphology from nanowires to c-oriented nanostructures such as nanorods. As a result, the structural, optical, electrical, optoelectronic, and electrochemical properties are enhanced. In fact, the series resistance is reduced by 80% to reach 2 Ω cm 2 , whereas the conductivity increases by 87%. The optical reflectivity is decreased by 61%, and the band gap narrowed from 3.42 eV to 3.19 eV. Using the electrochemical study, we evaluated the chemical capacity to be 12.6 * <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>6</mml:mn> </mml:mrow> </mml:msup> </mml:math> F, and the minority carrier lifetime reached 9.3 ms. The charge transfer resistance is reduced by 9 times, from 1393 to 173 Ω cm 2 , suggesting a faster charge transfer process due to the porous network, which improves the connection between interfaces. Thus, the power conversion efficiency was enhanced by 80% from 5% of 9.03%. The tests on the device show temperature resistance and stability.