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 enhanced by promoting charge transport and passivating defects. Graphite carbon nitride (g-C3N4) has shown promise as a modifier for optimizing energy level alignment and reducing defect density in PSCs. However, its preparation process can be complicated. In this study, we introduce a simple one-step calcination method for obtaining g-C3N4-modified TiO2 by adding urea to the TiO2 precursor. This modification simultaneously tunes the energy level alignment and passivates interface defects. The comprehensive research results confirm that the introduction of moderate amounts of g-C3N4 to TiO2 results in an ideal alignment of energy levels with perovskite, which improves the ability to separate and transfer charges. The g-C3N4-modified perovskite films also exhibit increased grain size and crystallinity, which in turn reduces intrinsic defects density and prolongs charge recombination time. As a result, 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 understanding of the interfacial engineering strategy and offers new insights into the development of high-performance PSCs.

Keywords: g-C3N4-modified TiO2, perovskite solar cell, energy level alignment, defects passivation, carrier dynamics