Improved Cu2ZnSnS4 thin film performance via Pb consumption layer

Abstract Adding a certain amount of Pb element into the perovskite solar cells can improve the devices' overall performance. However, there are few reports on the incorporation of Pb into Cu2ZnSnS4(CZTS) thin film solar cells. In this work, a novel absorber layer of CZTS:Pb thin film has been fabricated through sulfurization CZTS precursor with 15 nm Pb layer. XRD, Raman, and EDS characterizations exhibited that Pb was incorporated into CZTS and partially replaced Sn. Meanwhile, XPS measurement indicated that Pb was +4 valence and no distinct change of the CZTS chemical environment. SEM reveals that compact large grains almost span the whole thickness of the absorber when Pb is used as a consumption layer, while some fine grains and voids at the back contact exist in common CZTS films. The best efficiency of CZTS:Pb is 3.01% with the open-circuit voltage of 615.95 mV, the short-circuit current density of 14.74 mA/cm2 and the fill factor of 33.01%, which is mainly due to the Pb consumption layer improving the crystallinity of CZTS.