Abstract
Due to their outstanding optoelectronic properties, lead-based halide perovskite materials have been applied as efficient photoactive materials in solution-processed solar cells. Current ...record efficiencies offer the promise to surpass those of silicon solar cells. However, uncertainty about the potential toxicity of lead-based halide perovskite materials and their facile dissolution in water requires a search for new alternative perovskite-like materials. Thanks to the foresight of scientists and their experience in lead-based halide perovskite preparation, remarkable results have been obtained in a short period of time using lead-free perovskite compositions. However, the lower solar-to-energy conversion efficiency and long-term stability issues are serious drawbacks that hinder the potential progression of these materials. Here, we review and analyse strategies in the literature and the most promising solutions to identify the factors that limit the power conversion efficiency and long-term stability of lead-free tin-based perovskite solar cells. In the light of the current state-of-the-art, we offer perspectives for further developing these promising materials.
The application of self-assembled molecules (SAMs) as a charge selective layer in perovskite solar cells has gained tremendous attention. As a result, highly efficient and stable devices have been ...released with stand-alone SAMs binding ITO substrates. However, further structural understanding of the effect of SAM in perovskite solar cells (PSCs) is required. Herein, three triphenylamine-based molecules with differently positioned methoxy substituents have been synthesized that can self-assemble onto the metal oxide layers that selectively extract holes. They have been effectively employed in p-i-n PSCs with a power conversion efficiency of up to 20%. We found that the perovskite deposited onto SAMs made by para- and ortho-substituted hole selective contacts provides large grain thin film formation increasing the power conversion efficiencies. Density functional theory predicts that para- and ortho-substituted position SAMs might form a well-ordered structure by improving the SAM's arrangement and in consequence enhancing its stability on the metal oxide surface. We believe this result will be a benchmark for the design of further SAMs.
The use of self-assembled monolayers (SAMs) as selective charge extracting layers in perovskite solar cells is a great approach to replace the commonly used charge selective contacts, as they can ...easily modify the interface to enhance the final solar cell performance. Here, we report a novel synthetic approach of the commonly known zinc phtalocyanine (ZnPc) molecule TT1, widely employed in dye-sensitized solar cells and previously used in perovskite solar cells. TT1 is used as a p-type selective contact, and it demonstrates its ability to form SAM on top of the indium tin oxide (ITO) transparent electrode, obtaining higher efficiencies compared to Pedot:PSS based perovskite solar cells. The differences observed, with an enhanced open-circuit voltage and overall efficiency in TT1 devices are correlated with differences in energetics rather than recombination kinetics.
The use of self-assembled monolayers as selective charge extracting layers in perovskite solar cells is an efficient approach to replace the traditionally used contacts, as they can easily modify the interface to improve the solar cell performance.
A multi-walled carbon nanotubes-polypyrrole conducting polymer nanocomposite has been synthesized, characterized and used for the separation and preconcentration of lead at trace levels in water ...samples prior to its flame atomic absorption spectrometric detection. The analytical parameters like pH, sample volume, eluent, sample flow rate that were affected the retentions of lead(II) on the new nanocomposite were optimized. Matrix effects were also investigated. Limit of detection and preconcentration factors were 1.1µgL−1 and 200, respectively. The adsorption capacity of the nanocomposite was 25.0mg lead(II) per gram composite. The validation of the method was checked by using SPS-WW2 Waste water Level 2 certified reference material. The method was applied to the determination of lead in water samples with satisfactory results.
SEM micrograph image of (a) Pristine MWCNT and (b) nanocomposite of MWCNT/PPy. Display omitted
•Multiwalled carbon nanotubes-polypyrrole nanocomposite has been synthesized.•It was used as adsorbent for preconcentration of lead(II).•The analytical parameters were optimized.•The accuracy was evaluated by the analysis of the certified reference materials.•The method was applied to the determination of lead in water samples.
Current perovskite solar cell efficiency is close to silicon's record values. Yet, the roadblock for industrialization of this technology is its stability. The stability of the solar cell not only ...depends on the stability of the perovskite material itself but also notably on its contact layers and their interface with the perovskite, which plays a paramount role. This study rationalizes the design of new molecules to form self-assembled monolayers as a hole-selective contact. The new molecules increased the stability of the perovskite solar cells to maintain 80% of their initial PCE of 21% for 250 h at 85 °C under 1 sun illumination. The excellent charge collection properties as well as perovskite passivation effect enable the highly stable and efficient devices to demonstrate the vast potential of this new type of contact in photovoltaic application.
We have designed and synthesised two new carbazole based self-assembled molecules as hole-selective layers (HSLs) in p-i-n perovskite solar cells achieving high efficiency and high stability.
In this study, two novel fluorinated dibenzo
a
,
c
phenazine derivatives, 2,7-bis(5-bromo-4-hexylthiophen-2-yl)-11-fluorodibenzo
a
,
c
phenazine (TFBPz) and 2,7-bis(2,3-dihydrothieno3,4-
b
...1,4dioxin-5-yl)-11-fluorodibenzo
a
,
c
phenazine (EFBPz), were synthesized by coupling fluorodibenzo
a
,
c
phenazine (FBPz) with electron rich 3-hexylthiophene and ethylene dioxythiophene (EDOT) units. The monomers were polymerized electrochemically and their electrochemical, spectroelectrochemical and electrochromic behaviors were studied. Then, PTFBPz and PEDOT comprising electrochromic device was constructed and reported. Comparing both polymers in terms of their redox potentials, as expected, PEFBPz showed a lower oxidation potential due to the insertion of an electron rich EDOT unit into the polymer chain, which increased the electron density significantly. EDOT comprising dibenzo
a
,
c
phenazine derivative PEFBPz exhibited a red shifted neutral state absorption with lower optical band gap values compared to those of PTFBPz. Furthermore, three novel D-A type dibenzo
a
,
c
phenazine comprising polymers (
PBDT-TFBPz
,
PBDT-FBPz
and
PSi-TFBPz
) were synthesized chemically and all polymers were investigated in terms of their electrochromic and physicochemical behaviors.
In this study, five novel fluorinated dibenzo
a,c
phenazine comprising polymers were synthesized and characterized for electrochromic device applications.
The development of hole transport materials (HTMs) is a prolific area of research due to the application of these materials in various technologies such as organic light-emitting diodes (OLEDs) or ...perovskite solar cells (PSCs). HTMs have notably played a crucial role in the development of high-performance PSCs since in these devices, they not only ensure the collection and transport of holes to the counterelectrode but also play an important role on the device stability. In addition to the need for these materials to have good transport properties and to be easy to process, it is also of paramount importance to guarantee that their synthesis costs are reduced to allow them to be used on a large scale. In this work, we show that the use of a 9,10-bis(triisopropylsilyl)-ethynylanthracene (TIPS-anthracene) moiety as a π-conjugated core, in combination with electroactive arylamine moieties, allows us to obtain new efficient HTMs in only 2 or 4 steps after recrystallization. Solar cells fabricated with the hybrid perovskite (Cs0.05FA0.79MA0.16Pb(I0.84Br0.16)3 and these new HTMs exhibit power conversion efficiencies of up to 19.3% under AM1.5G solar illumination, which is close to the efficiency obtained with the reference compound 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (Spiro-OMeTAD) under the same conditions. Compared to other anthracene-based HTMs reported in recent years and used with perovskites of various compositions, our molecules, which are easy to prepare and purify, are more efficient.
The development of hole transport materials (HTMs) is a prolific area of research due to the application of these materials in various technologies such as organic lightemitting diodes (OLEDs) or ...perovskite solar cells (PSCs). HTMs have notably played a crucial role in the development of highperformance PSCs since in these devices, they not only ensure the collection and transport of holes to the counterelectrode but also play an important role on the device stability. In addition to the need for these materials to have good transport properties and to be easy to process, it is also of paramount importance to guarantee that their synthesis costs are reduced to allow them to be used on a large scale. In this work, we show that the use of a 9,10bis(triisopropylsilyl)-ethynylanthracene (TIPS-anthracene) moiety as a $\pi$-conjugated core, in combination with electroactive arylamine moieties, allows us to obtain new efficient HTMs in only 2 or 4 steps after recrystallization. Solar cells fabricated with the hybrid perovskite (Cs$_{0.05}$ FA$_{0.79}$ MA$_{0.16}$ Pb(I$_{0.84}$ Br$_{0.16}$)$_3$ and these new HTMs exhibit power conversion efficiencies of up to 19.3% under AM1.5G solar illumination, which is close to the efficiency obtained with the reference compound 2,2′,7,7′-tetrakis(N,N-di-pmethoxyphenylamine)-9,9′-spirobifluorene (Spiro-OMeTAD) under the same conditions. Compared to other anthracene-based HTMs reported in recent years and used with perovskites of various compositions, our molecules, which are easy to prepare and purify, are more efficient.
Stability issues could prevent lead halide perovskite solar cells (PSCs) from commercialization despite it having a comparable power conversion efficiency (PCE) to silicon solar cells. Overcoming ...drawbacks affecting their long‐term stability is gaining incremental importance. Excess lead iodide (PbI2) causes perovskite degradation, although it aids in crystal growth and defect passivation. Herein, we synthesized functionalized oxo‐graphene nanosheets (Dec‐oxoG NSs) to effectively manage the excess PbI2. Dec‐oxoG NSs provide anchoring sites to bind the excess PbI2 and passivate perovskite grain boundaries, thereby reducing charge recombination loss and significantly boosting the extraction of free electrons. The inclusion of Dec‐oxoG NSs leads to a PCE of 23.7 % in inverted (p‐i‐n) PSCs. The devices retain 93.8 % of their initial efficiency after 1,000 hours of tracking at maximum power points under continuous one‐sun illumination and exhibit high stability under thermal and ambient conditions.
Effectively managing excess lead iodide is crucial for enhancing perovskite stability. An innovative approach, tailoring functionalized oxo‐graphene nanosheets, stabilizes the perovskite structure and improves charge extraction. This leads to a significant boost in power conversion efficiency and long‐term stability in inverted (p‐i‐n) perovskite solar cells, providing a novel perspective on stabilizing photovoltaic devices.
