Inverted (pin) perovskite solar cells (PSCs) afford improved operating stability in comparison to their nip counterparts but have lagged in power conversion efficiency (PCE). The energetic losses responsible for this PCE deficit in pin PSCs occur primarily at the interfaces between the perovskite and the charge-transport layers. Additive and surface treatments that use passivating ligands usually bind to a single active binding site: This dense packing of electrically resistive passivants perpendicular to the surface may limit the fill factor in pin PSCs. We identified ligands that bind two neighboring lead(II) ion (Pb 2+ ) defect sites in a planar ligand orientation on the perovskite. We fabricated pin PSCs and report a certified quasi–steady state PCE of 26.15 and 24.74% for 0.05– and 1.04–square centimeter illuminated areas, respectively. The devices retain 95% of their initial PCE after 1200 hours of continuous 1 sun maximum power point operation at 65°C.
Compared with the n-i-p structure, inverted (p-i-n) perovskite solar cells (PSCs) promise increased operating stability, but these photovoltaic cells often exhibit lower power conversion efficiencies (PCEs) because of nonradiative recombination losses, particularly at the perovskite/C 60 interface. We passivated surface defects and enabled reflection of minority carriers from the interface into the bulk using two types of functional molecules. We used sulfur-modified methylthio molecules to passivate surface defects and suppress recombination through strong coordination and hydrogen bonding, along with diammonium molecules to repel minority carriers and reduce contact-induced interface recombination achieved through field-effect passivation. This approach led to a fivefold longer carrier lifetime and one-third the photoluminescence quantum yield loss and enabled a certified quasi-steady-state PCE of 25.1% for inverted PSCs with stable operation at 65°C for >2000 hours in ambient air. We also fabricated monolithic all-perovskite tandem solar cells with 28.1% PCE.
Organic/inorganic metal halide perovskites attract substantial attention as key materials for next-generation photovoltaic technologies due to their potential for low cost, high performance, and solution processability. The unique properties of perovskites and the rapid advances that have been made in solar cell performance have facilitated their integration into a broad range of practical applications, including tandem solar cells, building-integrated photovoltaics, space applications, integration with batteries and supercapacitors for energy storage systems, and photovoltaic-driven catalysis. In this Review, we outline notable achievements that have been made in these photovoltaic-integrated technologies. Outstanding challenges and future perspectives for the development of these fields and potential next-generation applications are discussed.
Surface passivation has driven the rapid increase in the power conversion efficiency (PCE) of perovskite solar cells (PSCs). However, state-of-the-art surface passivation techniques rely on ammonium ligands that suffer deprotonation under light and thermal stress. We developed a library of amidinium ligands, of interest for their resonance effect–enhanced N–H bonds that may resist deprotonation, to increase the thermal stability of passivation layers on perovskite surfaces. This strategy resulted in a >10-fold reduction in the ligand deprotonation equilibrium constant and a twofold increase in the maintenance of photoluminescence quantum yield after aging at 85°C under illumination in air. Implementing this approach, we achieved a certified quasi–steady-state PCE of 26.3% for inverted PSCs; and we report retention of ≥90% PCE after 1100 hours of continuous 1-sun maximum power point operation at 85°C.
The rapid surface oxidation of phosphorene under ambient conditions is considered to be a serious issue for many applications, but is used here as a strategy to achieve efficient heteroatom doping. Highly crystalline nitrogen-doped phosphorene (N-phosphorene) is prepared using a combination of ball milling and microwave techniques. The prepared N-doped phosphorene nanosheets showed outstanding electrocatalytic performance as a new type of non-metallic catalyst for nitrogen (N2) to ammonia (NH3) conversion, with an NH3 yield rate and faradaic efficiency (FE) of up to 18.79 μg h−1 mgCAT−1 and 21.51%, respectively, at a low overpotential (0 V) versus the reversible hydrogen electrode (RHE). Density functional theory calculations revealed that the high nitrogen reduction reaction (NRR) FEs originate from the increased hydrophobicity at the N and O doped phosphorene surfaces, which in turn hinders the competing hydrogen evolution reaction (HER) in an alkaline environment and promotes the NRR. This work not only introduces an efficient strategy to chemically functionalize 2D phosphorene, but also opens a new avenue in using N-doped phosphorene nanosheets as a metal-free catalyst.