Snaith group

Abstract:

Perovskite solar cells represent a promising technology in the photovoltaic industry due to their high power conversion efficiency, potential for cost-effective manufacturing and versatile applications. The most stable and efficient perovskites to date rely on lead (Pb), raising concerns about leaching into the environment; however Pb release so far has only been quantified under laboratory conditions, and no field-based assessment under real outdoor expsosure has yet evaluated this risk. The present study quantified Pb leaching from various metal-halide perovskite compositions, device stacks and encapsulation approaches in a rooftop installation for up to 9 months. Pb leaching was low across all tested configurations, even in intentionally damaged materials. Glass–glass encapsulated tandem devices shattered by hail and plastic-encapsulated samples damaged by 100 µm pinholes released only 0.07% ± 0.01% and 0.15% ± 0.14% of their initial Pb, respectively, likely due to the slow diffusion of Pb cations in water. The highest leaching (4.81% ± 0.02%) occurred in unlaminated laboratory devices, demonstrating the importance of proper lamination. A self-developed freeware web tool was used to calculate predicted soil concentrations and evaluate potential impacts. Even for unlaminated devices, concentrations would only slightly exceed natural background levels (5.6 mg kg−1 increase), with negligible effects on soil fertility. A hypothetical worst-case scenario assuming a 1000 nm thick perovskite layer and complete Pb leaching onto a narrow strip of soil predicted a negative impact on soil fertility; however remediation would still not be required under Swiss environmental regulations. Overall, current industry-standard encapsulation limits Pb leaching to levels that almost completely mitigate negative impacts on soil health.

Abstract:

<jats:p>This study pioneers a solvent-additive cascade strategy to achieve crystallographically homogenous perovskite films, breaking the efficiency–stability trade-off by harnessing facet-dependent properties for record performance.</jats:p>

Abstract:

Semi-transparent perovskite solar cells (ST-PSCs) have shown great potential in building-integrated photovoltaics. However, the performance of ST-PSCs is still far from achieving their true potential. Herein, a functional additive, [4-(trifluoromethyl)phenyl] sulfonyl chloride (TFBSC), is incorporated into the perovskite precursor solution to regulate the crystallization process and reduce defects in the perovskite films. The addition of TFBSC improves the perovskite film morphology and increases the charge carrier lifetime and photoluminescence quantum efficiency, compared with the control perovskite films. As a result, the champion device modified with TFBSC shows a power conversion efficiency (PCE) of 14.75% with a light utilization efficiency (LUE) of 3.92%, whereas the control device shows PCE and LUE values of 10.71% and 2.96%, respectively. Moreover, the unencapsulated TFBSC-modified device retains ∼90% of its initial PCE after 1500 h of storage under ambient conditions (relative humidity of ∼30%–40%). These findings could provide new avenues to develop high performance ST-PSCs for smart building applications.

Abstract:

Monolithic perovskite–organic tandem solar cells (POTSCs) have attracted considerable attention in recent years due to their compatible fabrication routes and advances in single-cell efficiencies. To further boost the performance of POTSCs, reducing the voltage losses that mainly arise from wide bandgap (WBG, >1.7 eV) perovskite subcells and interconnecting layers (ICLs) is critical. Here, a new ICL with a configuration of C60/YbO x /Au/MoO x is demonstrated for constructing the monolithic POTSC. The YbO x -based ICL benefits from an ohmic contact and high transparency, resulting in improved POSTC performance. The champion device presents a PCE of 23.2% owing to a high V OC of 2.11 V (approximately equal to the sum of individual V OC’s of the subcells) without compromising the short-circuit current density and fill factors. This work opens an avenue for developing efficient ICLs in POTSCs.