Researchers from Taiwan's National Cheng Kung University and Chung Yuan Christian University have developed an interface-engineering strategy to overcome key efficiency bottlenecks in mesoporous perovskite solar cells by introducing APTS-functionalized reduced graphene oxide (APTS-rGO) into the electron transport structure.
The team focused on addressing persistent limitations associated with mesoporous TiO2 (mp-TiO2), which, despite its widespread use as an electron transport layer, suffers from interfacial resistance, energy level mismatch, and surface defect states that promote charge recombination. These effects suppress key photovoltaic parameters, including open-circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF).
To resolve these issues, the researchers incorporated reduced graphene oxide functionalized with 3-aminopropyltriethoxysilane (APTS). This surface modification plays multiple roles: it passivates TiO2 surface defects, improves perovskite crystal growth by increasing porosity, and tunes energy band alignment at the interface. Kelvin probe measurements showed that APTS functionalization shifts the rGO work function from 4.567 eV to 4.148 eV, enabling better alignment with the perovskite absorber and facilitating charge extraction.
The modified interface reduces charge transfer resistance and suppresses interfacial charge accumulation, leading to more efficient carrier transport. Devices fabricated via spin coating of the APTS-rGO layer delivered the best performance, achieving a Voc of 1.04 V, a Jsc of 19.9 mA/cm², an FF of 70.39%, and a power conversion efficiency (PCE) of 14.6%. This represents an 18% improvement compared to conventional mp-TiO2-based perovskite solar cells.
These results highlight the importance of interface engineering in mesoporous architectures and demonstrate how chemical functionalization of interlayers can simultaneously optimize morphology, energetics, and charge dynamics in perovskite photovoltaics.
