Perovskite solar cells (PSCs) have become a promising photovoltaic (PV) technology, where the evolution of the electron‐selective layers (ESLs), an integral part of any PV device, has played a ...distinctive role to their progress. To date, the mesoporous titanium dioxide (TiO2)/compact TiO2 stack has been among the most used ESLs in state‐of‐the‐art PSCs. However, this material requires high‐temperature sintering and may induce hysteresis under operational conditions, raising concerns about its use toward commercialization. Recently, tin oxide (SnO2) has emerged as an attractive alternative ESL, thanks to its wide bandgap, high optical transmission, high carrier mobility, suitable band alignment with perovskites, and decent chemical stability. Additionally, its low‐temperature processability enables compatibility with temperature‐sensitive substrates, and thus flexible devices and tandem solar cells. Here, the notable developments of SnO2 as a perovskite‐relevant ESL are reviewed with emphasis placed on the various fabrication methods and interfacial passivation routes toward champion solar cells with high stability. Further, a techno‐economic analysis of SnO2 materials for large‐scale deployment, together with a processing‐toxicology assessment, is presented. Finally, a perspective on how SnO2 materials can be instrumental in successful large‐scale module and perovskite‐based tandem solar cell manufacturing is provided.
Notable developments of SnO2 as an electron‐selective layer for efficient perovskite solar cells (PSCs) are reviewed, along with an overview of the fabrication methods and interfacial passivation routes. Furthermore, techno‐economic and toxicology analyses of SnO2 are discussed for possible large‐scale deployment of PSCs. Finally, the role of SnO2 in scaled module and tandem solar cell production is revealed.
Hybrid organic–inorganic semiconducting perovskite photovoltaic cells are usually coupled with organic hole conductors. Here, we report planar, inverse CH3NH3PbI3–x Cl x -based cells with inorganic ...hole conductors. Using electrodeposited NiO as hole conductor, we have achieved a power conversion efficiency of 7.3%. The maximum V OC obtained was 935 mV with an average V OC value being 785 mV. Preliminary results for similar cells using electrodeposited CuSCN as hole conductor resulted in devices up to 3.8% in efficiency. The ability to obtain promising cells using NiO and CuSCN expands the presently rather limited range of available hole conductors for perovskite cells.
A fluoride boostThe wide-bandgap perovskite layer in perovskite-silicon tandem solar cells is still limited by high interface recombination at the electron extraction interface. Liu et al. show that ...adding an ultrathin magnesium fluoride interlayer between the perovskite and C60 electron transport layer during growth facilitates mitigated nonradiative recombination. An analysis of electronic structural data showed that conduction band bending of the perovskite and C60 facilitated electron extraction. A monolithic perovskite-silicon tandem solar cell with a certified power conversion efficiency of 29.3% retained about 95% of its initial performance for 1000 hours. —PDS
Highly reproducible and reversible thermochromic nature of dihydrated methylammonium lead iodide is found. A wide bandgap variation of the material (∼2 eV) is detected between room temperature and 60 ...°C under ambient condition as a result of phase transition caused by moisture absorption and desorption. In situ X-ray diffraction and Fourier transform infrared spectroscopy studies are performed to understand the mechanistic behavior during the phase transition. This thermochromic property is further explored as absorber material in mesostructured solar cells. Temperature-dependent reversible power conversion efficiency greater than 1% under standard test conditions is demonstrated; revealing its potential applicability in building integrated photovoltaics.
Highly efficient perovskite solar cells (PSCs) fabricated in the classic n–i–p configuration generally employ triphenylamine-based hole-transport layers (HTLs) such as spiro-OMeTAD, PTAA, and ...poly-TPD. Controllable doping of such layers has been critical to achieve increased conductivity and high device performance. To this end, LiTFSI/tBP doping and subsequent air exposure is widely utilized. However, this approach often leads to low device stability and reproducibility. Departing from this point, we introduce the Lewis acid tris(pentafluorophenyl)borane (TPFB) as an effective dopant, resulting in a significantly improved conductivity and lowered surface potential for triphenylamine-based HTLs. Here, we specifically investigated spiro-OMeTAD, which is the most widely used HTL for n–i–p devices, and revealed improved power conversion efficiency (PCE) and stability of the PSCs. Further, we demonstrated the applicability of TPFB doping to other triphenylamine-based HTLs. Spectroscopic characterizations reveal that TPFB doping results in significantly improved charge transport and reduced recombination losses. Importantly, the TPFB-doped perovskite devices retained near 85% of the initial PCE after 1000 h of storage in the air, while the conventional LiTFSI-doped device dropped to 75%. Finally, we give insight into utilizing other similar molecular dopants such as fluorine-free triphenylborane and phosphorus-centered tris(pentafluorophenyl)phosphine (TPFP) by density functional theory analysis underscoring the significance of the central boron atom and fluorination in TPFB for the formation of Lewis acid–base adducts.
Perovskite-based solar cells have attracted much recent research interest with efficiency approaching 20%. While various combinations of material parameters and processing conditions are attempted ...for improved performance, there is still a lack of understanding in terms of the basic device physics and functional parameters that control the efficiency. Here we show that perovskite-based solar cells have two universal features: an ideality factor close to two and a space-charge-limited current regime. Through detailed numerical modeling, we identify the mechanisms that lead to these universal features. Our model predictions are supported by experimental results on solar cells fabricated at five different laboratories using different materials and processing conditions. Indeed, this work unravels the fundamental operation principle of perovskite-based solar cells, suggests ways to improve the eventual performance, and serves as a benchmark to which experimental results from various laboratories can be compared.
Concepts surrounding transfusions are changing at its core, especially toward minimizing transfusions firstly because blood is a finite resource and secondly because a dose-response pattern has been ...established to each unit of blood transfused. ...the recently recommended practice of transfusing single-unit red blood cell for nonbleeding hospitalized patients, followed by the clinical reassessment to determine the need for transfusion was considered appropriate, and this reassessment will also guide the decision on whether to retest the Hb levels7. ...we feel that single-unit transfusion decisions are safe in stable hospitalized obstetric patients, and the decision to transfuse subsequent units should be prescribed only after reassessment.
The recent evolution of solution-processed hybrid organic–inorganic perovskite-based photovoltaic devices opens up the commercial avenue for high-throughput roll-to-roll manufacturing technology. To ...circumvent the thermal limitations that hinder the use of metal oxide charge transport layers on plastic flexible substrates in such technologies, we employed a relatively low-power nitrogen plasma treatment to achieve compact SnO2 thin-film electrodes at near room temperature. The perovskite photovoltaic devices thus fabricated using N2 plasma-treated SnO2 performed on par with thermally annealed SnO2 electrodes and resulted in a power conversion efficiency (PCE) of ca. 20.3% with stabilized power output (SPO) of ca. 19.1% on rigid substrates. Furthermore, the process is extended to realize flexible perovskite solar cells on indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrates with champion PCE of 18.1% (SPO ca. 17.1%), which retained ca. 90% of its initial performance after 1000 bending cycles. Our investigations reveal that deep ultraviolet irradiation associated with N2 and N2O plasma emission plays a major role in obtaining good quality metal oxide thin films at lower temperatures and offers promise toward facile integration of a wide variety of metal oxides on flexible substrates.
•Old world bluestem (OWB) grass contained measurable amounts of essential oils.•Acorenone-B was present in the greatest concentration over three years.•Presence of camphene, limonene, and naphthalene ...may be associated with repellency of red imported fire ants.
Bothriochloa spp. include aromatic grasses that produce essential oils. Some of these grasses are reported to repel economically important insects. Leaves, stems, and seedheads of ‘WW-B.Dahl’ old world bluestem Bothriochloa bladhii (Retz) S.T. Blake were sampled during 3 years. Quantitative analysis by GC and GC–MS methods revealed a total of 172 compounds from methylation method, and 105 compounds from steam distillation method. Acorenone-B spiro4.5dec-6-en-8-one, 1,7-dimethyl-4-(1-methylethyl)- was in greatest concentration in both methods; however, this compound was detected on only one date (12 August) out of three collection dates extracted by steam distillation. Twenty-two compounds were detected by simple solvent extraction, in which acorenone-B was in greatest concentration in seedheads and least in stems. Diethylhexyl adipate was in highest concentration in stems and least in seedheads among the oils extracted by simple solvent. Camphene and limonene were present in the samples that contained seedheads. Naphthalene, a known insect deterrent, was detected in oils extracted from all methods and in all plant parts. Old world bluestem grass contained measurable amounts of essential oils that may be associated with previously observed repellency of red imported fire ants (Solenopsis invicta Buren).
Slot‐die coating is highly promising for scaled deposition of metal halide perovskite thin films. However, the power conversion efficiencies (PCEs) of slot‐die‐prepared perovskite solar cells (PSCs) ...still lag behind their spin‐casted counterparts. To resolve this issue, the crystal size and quality of slot‐die‐coated methylammonium lead triiodide (MAPbI3) perovskite films are dramatically improved via additive engineering using potassium thiocyanate (KSCN). The modified micrometer‐thick films have an average grain size of ≈11 μm and charge‐carrier parameters that are comparable with single‐crystal perovskites, such as a 1.89 μs lifetime, 136.65 ± 31.52 cm2 V−1 s−1 mobility, and 25.15 ± 3.55 μm diffusion length. Exploiting these enhanced properties, planar inverted PSCs with negligible hysteresis are fabricated and an average and a maximum PCE of 20.14% and 21.38%, respectively, are achieved which are among the highest reported values for slot‐die‐coated PSCs. Notably, our devices have a narrow PCE distribution along the slot‐die coating axis, highlighting slot‐die coating's promise to fabricate large‐scale, high‐performance PSCs.
Assisted by potassium thiocyanate (KSCN) as additive, slot‐die‐coated MAPbI3 perovskite films are prepared with ultra‐large grain size of up to 11 μm and remarkable charge‐carrier diffusion lengths up to 25.15 μm. Using these films, perovskite solar cells with a power conversion efficiency of 21.38% with negligible hysteresis are obtained with a device stack entirely fabricated using scalable methods.
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