Effect of incorporation of highly‐ordered a‐Ge:H nanoparticles on the performance of perovskite solar cells

Abstract

To improve light absorption, in this study, the narrow band gap highly-ordered free-standing hydrogenated amorphous germanium nanoparticles (a-Ge:H NPs) were introduced into the CH3NH3PbI3-xClx films. Here, the NPs were fabricated by means of the radio frequency plasma enhanced chemical vapour deposition system. The effects of hydrogen dilution ratio (RH) on the microstructure and bonding configuration of a-Ge:H NPs were investigated by Raman, transmission electron microscopy and Fourier transform infrared spectroscopy measurements. As RH increases, an improvement in the structure order of a-Ge:H NPs was observed. Compared with the pure CH3NH3PbI3-xClx films, the light absorption of the hybrid a-Ge:H NPs/CH3NH3PbI3-xClx active layers was improved, and the surface coverage of the hybrid active layers nearly reached 100%. This new finding provided a novel way to solve the universal unfavourable surface coverage problem that existed in the ultrasonic spray-coating process. Meanwhile, compared with the device that is based on pure CH3NH3PbI3-xClx films, due to the enhanced light absorption in the visible range, a approximate to 14.6% enhancement in the power conversion efficiency was achieved based on the hybrid a-Ge:H NPs/CH3NH3PbI3-xClx active layers.