Graphdiyne oxide modified nano CuO as inorganic hole transport layer for efficient and stable organic solar cells

Abstract With the rapid development of organic solar cells (OSCs), the stability of devices has gradually attracted researcher’s attention. The characteristics of hole transport layer (HTL) have a crucial influence on the stability and performance of OSCs. Inorganic semiconductor CuO nanomaterials with high transmittance, good stability, low cost and rich raw materials were chosen as hole transport materials for the fabrication of high-efficiency OSCs. In this work, graphdiyne oxide (GDYO) as an interface modifier was introduced into CuO nanofilm to improve its conductivity and reduce the contact resistance between HTL and the active layer. As a result, the PM6:Y6 based OSCs with CuO (GDYO) as HTL exhibit a high power conversion efficiency (PCE) of 16.61% with simultaneous improvements on short-circuit current density and fill factor compared with the unmodified devices. The performance improvement of the device is mainly attributed to the increased hole mobility and reduced charge recombination by adding an appropriate amount of GDYO. To prove its universality, a PCE of 16.74% (PM6:Y6-BO-4Cl) and a PCE of 9.19% (PTB7-Th:PC ₇₁ BM) of OSCs were obtained based on CuO (GDYO) as HTL. CuO (GDYO) based OSCs have obtained the highest efficiency among inorganic HTLs when using same active layer materials, and are also better than the reported poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) based devices. In addition, the stability of all CuO (GDYO) based OSCs can still be maintained above 65% after 30 h in air without any encapsulation. The results suggest that GDYO modified CuO as HTL has great potential in fabrication of high efficient and stable OSCs.