Search

Defect‐mediated recombination losses limit the open‐circuit voltage (VOC) of perovskite solar cells (PSCs), negatively affecting the device's performance. Bulk and dimensional engineering have both been reported as promising strategies to passivate shallow defects, thus improving the photovoltaic conversion efficiency (PCE). Here, a combined bulk and surface treatment employing chlorine‐based compounds is employed. Methylammonium chloride (MACl) is used as a bulk additive, while 4‐methylphenethylammonium chloride (MePEACl) is deposited onto the perovskite surface to produce a low‐dimensional perovskite (LDP) and reduce nonradiative recombination. Through structural and morphological investigations, it can be confirmed that bulk and surface doping have a beneficial effect on the film morphology and its overall quality, while electroluminescence (EL) and photoluminescence (PL) analyses demonstrate an increased and more homogeneous emission. Applying this double passivation strategy in PSC fabrication, a boost is observed in both the short‐circuit current density and the VOC of the devices, achieving a champion 21.4% PCE while improving device stability. [ABSTRACT FROM AUTHOR]

In the search for stable perovskite photovoltaic technology, carbon‐based perovskite solar cells (C‐PSCs) represent a valid, stable solution for near‐future commercialization. However, a complete understanding of the operational device stability calls for assessing the device robustness under thermal stress. Herein, the device response is monitored upon a prolonged thermal cycle aging (heating the device for 1 month up to 80 °C) on state‐of‐the‐art C‐PSCs, often neglected, mimicking outdoor conditions. Device characterization is combined with in‐house‐developed advanced modeling of the current–voltage characteristics of the C‐PSCs using an iterative fitting method based on the single‐diode equation to extrapolate series (RS) and shunt (RSH) resistances. Two temperature regimes are identified: Below 50 °C C‐PSCs are stable, and switching to 80 °C a slow device degradation takes place. This is associated with a net decrease of the device RSH, whereas the RS is unaltered, pointing to interface deterioration. Indeed, structural and optical analyses, by means of X‐ray diffraction and photoluminescence studies, reveal no degradation of the perovskite bulk, providing clear evidence that perovskite/contact interfaces are the bottlenecks for thermal‐induced degradation in C‐PSCs. [ABSTRACT FROM AUTHOR]