Carbon nanotube-integrated triple-junction perovskite-based tandem solar cell for enhanced photovoltaic performance

The global demand for sustainable energy has accelerated the advancement of high-efficiency photovoltaic technologies, with multi-junction tandem solar cells emerging as a leading solution. Among these, perovskite solar cells (PSCs) have gained prominence due to their high absorption coefficient, tunable bandgap, superior carrier mobility, long diffusion length, and low fabrication cost. However, achieving both high efficiency and long-term stability in tandem architectures remains challenging. Carbon-based nanomaterials have been widely employed in PSCs to enhance performance and stability owing to their exceptional optoelectronic properties. This study proposes an innovative triple-junction perovskite-based tandem solar cell (PTSC) incorporating carbon nanotube (CNT) to address these challenges. The baseline PTSC—comprising BiFeO₃, MAPbI₃, and InGaAs as top, middle, and bottom absorbers—achieved a simulated power conversion efficiency (PCE) of 26.27%. Integrating the CNT layer between MAPbI₃ and InGaAs extended spectral absorption beyond 800 nm into the near-infrared region and improved carrier transport. Comprehensive Silvaco TCAD simulations and optimization of absorber and tunnel junction parameters —focusing on thickness, band alignment, and doping concentrations—improved the PCE to 30.52%, with Jsc = 25 mA/cm², Voc = 1.35 V, and FF = 89.45%. The CNT layer significantly increased photocurrent generation and broadened quantum efficiency up to 1600 nm. Additionally, variations in CNT thickness and doping concentration on device performance were analyzed. The results demonstrate the multifunctional role of CNTs as both absorbers and transport mediators, providing an effective route toward enhanced optoelectronic performance in tandem photovoltaics.