Fill Factor Assessment in Hole Selective Layer Free Carbon Electrode?Based Perovskite Solar Cells with 15.5% Certified Power Conversion Efficiency

Carbon-electrode-based perovskite solar cells (C-PSCs) are promising candidates for commercialization due to their high stability. However, the absence of a hole selective layer (HSL) often limits performance, yielding low fill factors (FFs). Herein, certified FF 78.8% obtained through HSL-free C-PSCs is focused. This found approach highest values reported metal-electrode-based PSCs employing highly HSLs. The loss mechanisms affecting in fully printed thus investigated. Methods commonly used analyze and quantify impact recombination transport losses on established photovoltage devices assessed, applicability examined. In improved devices, non-radiative contributes only 3%abs with respect radiative limit, which attributed an optimal diode ideality factor approaching 1.0. Moreover, contributions shunt resistive determined be negligible. Interfacial series resistance at perovskite/carbon interface identified as main channel, highlighting importance quality contact between back-contact electrode.