High performance perovskite solar cells using CuS supraparticles incorporated hole transport layers.

We disclose novel photovoltaic device physics and present details of device mechanisms by investigating perovskite solar cells (PSCs) incorporating CuS@SiO supraparticles (SUPs) into Spiro-OMeTAD based hole transport layers (HTLs). High quality colloidal CuS nanocrystals (NCs) were prepared using a hot-injection approach. Multiple CuS NCs were further embedded in silica to construct a CuS@SiO SUP. CuS@SiO SUPs were blended into Spiro-OMeTAD based HTLs with different weight ratios. Theoretical and experimental results show that the very strong light scattering or reflecting properties of CuS@SiO SUPs blended in the PSC device in a proper proportion distribute to increase the light energy trapped within the device, leading to significant enhancement of light absorption in the active layer. Additionally, the incorporated CuS@SiO SUPs can also promote the electrical conductivity and hole-transport capacity of the HTL. Significantly larger conductivity and higher hole injection efficiency were demonstrated in the HTM with the optimal weight ratios of CuS@SiO SUPs. As a result, efficient CuS SUPs based PSC devices were obtained with average power conversion efficiency (PCE) of 18.21% at an optimal weight ratio of CuS SUPs. Compared with PSC solar cells without CuS@SiO SUPs (of which the average PCE is 14.38%), a remarkable enhancement over 26% in average PCE was achieved. This study provides an innovative approach to efficiently promote the performance of PSC devices by employing optically stable, low-cost and green p-type semiconductor SUPs.