A simple strategy to obtain graphitic carbon nitride modified TiO₂ layer for efficient perovskite solar cells

Abstract

The power conversion efficiency (PCE) of perovskite solar cells (PSCs) can be improved through the concurrent strategies of enhancing charge transfer and passivating defects. Graphite carbon nitride (g-C3N4) has been demonstrated as a promising modifier for optimizing energy level alignment and reducing defect density in PSCs. However, its preparation process can be complicated. A simple one-step calcination approach was used in this study to prepare g-C3N4-modified TiO2 via the incorporation of urea into the TiO2 precursor. This modification simultaneously tunes the energy level alignment and passivates interface defects. The comprehensive research confirms that the addition of moderate amounts of g-C3N4 to TiO2 results in an ideal alignment of energy levels with perovskite, thereby enhancing the ability to separate and transfer charges. Additionally, the g-C3N4-modified perovskite films exhibit an increase in grain size and crystallinity, which reduces intrinsic defects density and extends charge recombination time. Therefore, the g-C3N4-modified PSC achieves a champion PCE of 20.00%, higher than that of the control PSC (17.15%). Our study provides a systematic comprehension of the interfacial engineering strategy and offers new insights into the development of high-performance PSCs.

Simultaneous Defect Passivation and Electric Level Regulation with Rubidium Fluoride for High-Efficiency CsPbI2Br Perovskite Solar Cells

“…21−23 Apart from the detrimental defects, the imperfect band alignment across the interface usually disturbs charge carrier diffusion, eventually resulting in low V OC and PCE. 24,25 Furthermore, the massive defects and pinholes in CsPbI 2 Br perovskite films could accelerate ion migration and allow moisture to unscrupulously immerse into the perovskite film, resulting in undesirable stability for the devices. 26 To obtain highly efficient and stable CsPbI 2 Br PSCs, various approaches have been applied to prepare high-quality perovskite films and stabilize the lattice structure, such as dopant engineering, 27,28 dimension regulation, 29 and interface engineering.…”

“…At present, the PCE of CsPbI 2 Br-based PSCs is still far from its theoretical limitations, which were mainly attributed to the poor quality of the perovskite film . As is known to all, the CsPbI 2 Br perovskite films are always prepared by solution processing, and they contain substantial disordered structures, such as grain boundary defects and crystallographic defects at the surface. , Previous studies have demonstrated that the inferior defects derived from solution processing would cause severe nonradiative recombination of photoinduced charges. − Apart from the detrimental defects, the imperfect band alignment across the interface usually disturbs charge carrier diffusion, eventually resulting in low V OC and PCE. , Furthermore, the massive defects and pinholes in CsPbI 2 Br perovskite films could accelerate ion migration and allow moisture to unscrupulously immerse into the perovskite film, resulting in undesirable stability for the devices . To obtain highly efficient and stable CsPbI 2 Br PSCs, various approaches have been applied to prepare high-quality perovskite films and stabilize the lattice structure, such as dopant engineering, , dimension regulation, and interface engineering. − Among all strategies, surface modification has been regarded as a convenient and effective way to eliminate the numerous defects at surface and grain boundaries and strengthen the stability of perovskite films .…”