Enhancing the photocurrent response of cesium bismuth iodide perovskite using a CuO nanocones array as the hole collecting layer

• CuO-NCA is used as a hole collecting layer in the Cs 3 Bi 2 I 9 perovskite photodetector. • CuO-NCA greatly increases the contact area between the Cs 3 Bi 2 I 9 perovskite and CuO. • The transfer of the holes is more effective and straightforward in aligned nanocones. A CuO nanocones array (NCA) is introduced as a hole collecting layer for a top light-incident Cs 3 Bi 2 I 9 perovskite photodetector. Its photocurrent response ( i - t ) shows that the photocurrent of the CuO-NCA/Cs 3 Bi 2 I 9 device, and its responsivity, are one order of magnitude higher than that of the CuO thin film/Cs 3 Bi 2 I 9 based device. Moreover, the increased interfacial area between the Cs 3 Bi 2 I 9 and CuO-NCA facilitates hole collecting. While the transfer of the photogenerated holes is more effective and straightforward in aligned nanocones, which contributes to a larger photocurrent. The dynamics of the photo-generated charge transport also indicates a significantly improved charge transfer and a decreased charge recombination in the CuO-NCA/Cs 3 Bi 2 I 9 based device.