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.
In this work, reduced graphene oxide (rGO) was chemically modified using 3-aminopropyltriethoxysilane (APTS), a silane coupling agent with both amine and silane functional groups. This dual functionality enables strong bonding with oxide surfaces such as TiO2 while simultaneously improving compatibility with the perovskite layer.
The APTS modification allows precise tuning of the rGO electronic properties. Kelvin probe analysis confirmed a shift in work function from 4.567 eV to 4.148 eV after functionalization, improving band alignment between the electron transport layer and the perovskite absorber. This adjustment reduces interfacial energy barriers and promotes faster electron extraction.
Beyond energy alignment, the APTS-rGO layer also enhances interfacial contact and reduces defect-mediated recombination. Graphene’s inherently high carrier mobility - up to 25,000 cm²/(V·s) in ideal conditions - supports efficient charge transport, while the functionalized surface improves interfacial bonding and stability.
When integrated into mesoporous TiO2-based perovskite solar cells, the APTS-rGO layer led to notable performance gains. The optimized devices achieved a Voc of 1.04 V, Jsc of 19.9 mA/cm², FF of 70.39%, and a PCE of 14.6%, corresponding to an 18% improvement over reference devices. The enhancements are attributed to reduced charge transfer resistance, minimized recombination, and improved carrier extraction efficiency.
This study reinforces the role of graphene derivatives as tunable, solution-processable interfacial materials and demonstrates how chemical functionalization can unlock their full potential in next-generation photovoltaic devices.
