A planar perovskite solar cell that incorporates a nanocarbon hole‐extraction layer is demonstrated for the first time by an inkjet printing technique with a precisely controlled pattern and ...interface. By designing the carbon plus CH3NH3I ink to transform PbI2 in situ to CH3NH3PbI3, an interpenetrating seamless interface between the CH3NH3PbI3 active layer and the carbon hole‐extraction electrode was instantly constructed, with a markedly reduced charge recombination compared to that with the carbon ink alone. As a result, a considerably higher power conversion efficiency up to 11.60 % was delivered by the corresponding solar cell. This method provides a major step towards the fabrication of low‐cost, large‐scale, metal‐electrode‐free but still highly efficient perovskite solar cells.
Inkjet‐printing solar cells: By designing carbon plus CH3NH3I ink to transform PbI2 in situ to CH3NH3PbI3, an interpenetrating seamless interface between the CH3NH3PbI3 active layer and the C hole‐extraction electrode was instantly constructed, resulting in a 11.60 % efficient, planar perovskite solar cell.
A photoanode based on ZnO nanotetrapods, which feature good vectorial electron transport and network forming ability, has been developed for efficient photoelectrochemical water splitting. Two ...strategies have been validated in significantly enhancing light harvesting. The first was demonstrated through a newly developed branch-growth method to achieve secondary and even higher generation branching of the nanotetrapods. Nitrogen-doping represents the second strategy. The pristine ZnO nanotetrapod anode yielded a photocurrent density higher than those of the corresponding nanowire devices reported so far. This photocurrent density was significantly increased for the new photoanode architecture based on the secondary branched ZnO nanotetrapods. After N-doping, the photocurrent density enjoyed an even more dramatic enhancement to 0.99 mA/cm2 at +0.31 V vs Ag/AgCl. The photocurrent enhancement is attributed to the greatly increased roughness factor for boosting light harvesting associated with the ZnO nanotetrapod branching, and the increased visible light absorption due to the N-doping induced band gap narrowing of ZnO.
Cost‐effective electrocatalysts for the oxygen evolution reaction (OER) are critical to energy conversion and storage processes. A novel strategy is used to synthesize a non‐noble‐metal‐based ...electrocatalyst of the OER by finely combining layered FeNi double hydroxide that is catalytically active and electric conducting graphene sheets, taking advantage of the electrostatic attraction between the two positively charged nanosheets. The synergy between the catalytic activity of the double hydroxide and the enhanced electron transport arising from the graphene resulted in superior electrocatalytic properties of the FeNi‐GO hybrids for the OER with overpotentials as low as 0.21 V, which was further reduced to 0.195 V after the reduction treatment. Moreover, the turnover frequency at the overpotential of 0.3 V has reached 1 s−1, which is much higher than those previously reported for non‐noble‐metal‐based electrocatalysts.
A low‐cost and highly active electrochemical catalyst for the oxygen evolution reaction is created by alternatively stacking FeNi double hydroxide cation layers with GO anionic sheets. The advanced performance of the catalyst stems from the intrinsic catalytic activity of the layered FeNi double hydroxide and is boosted by the high electric conductivity of the adjoining graphene sheets.
Since the electrocatalytic activity of layered molybdenum disulfide (MoS2) for hydrogen evolution reaction (HER) closely depends on its exposed edges, the morphology and size of the material are ...critically important. Herein, we introduce a novel solvent-evaporation-assisted intercalation method to fabricate the hybrid of alternating MoS2 sheets and reduced graphene oxide layers, in which the nanosize of the MoS2 nanosheets can be effectively controlled by leveraging the confinement effect within the two-dimensional graphene layers. Significantly, the resulting MoS2/reduced graphene oxide (RGO) composite shows excellent catalytic activity for HER characterized by higher current densities and lower onset potentials than the conventional pre-exfoliated RGO supported MoS2 nanosheets. Further experiments on the effect of oxidation degree of graphene, the crystallinity of MoS2, and the exposed active site density on the HER performance of the MoS2/RGO composites show that there is an optimum condition for the catalytic activity of HER due to a balance between the numbers of exposed active sites of MoS2 and the internal conductive channels provided by graphene.
Inorganic CsSnI3 with low toxicity and a narrow bandgap is a promising photovoltaic material. However, the performance of CsSnI3 perovskite solar cells (PSCs) is much lower than that of Pb‐based and ...hybrid Sn‐based (e.g., CsPbX3 and CH(NH2)2SnX3) PSCs, which may be attributed to its poor film‐forming property and the deep traps induced by Sn4+. Here, a bifunctional additive carbazide (CBZ) is adapted to deposit a pinhole‐free film and remove the deep traps via two‐step annealing. The lone electrons of the NH2 and CO units in CBZ can coordinate with Sn2+ to form a dense film with large grains during the phase transition at 80 °C. The decomposition of CBZ can reduce Sn4+ to Sn2+ during annealing at 150 °C to remove the deep traps. Compared with the control device (4.12%), the maximum efficiency of the CsSnI3:CBZ PSC reaches 11.21%, which is the highest efficiency of CsSnI3 PSC reported to date. A certified efficiency of 10.90% is obtained by an independent photovoltaic testing laboratory. In addition, the unsealed CsSnI3:CBZ devices maintain initial efficiencies of ≈100%, 90%, and 80% under an inert atmosphere (60 days), standard maximum power point tracking (650 h at 65 °C), and ambient air (100 h), respectively.
An additive‐assisted two‐step annealing process was developed for high‐performance CsSnI3 perovskite solar cells (PSCs). The carbazide (CBZ) can slow down crystallization for dense coverage at 80 °C. After further annealing at 150 °C, the uncoordinated CBZ reduces Sn4+ to Sn2+ with few deep traps. The efficiency of CsSnI3:CBZ is 11.21%, which is the highest performance for CsSnI3‐based PSCs to date.
The preparation of perovskite components (PbI2 and SnI2) using waste materials is of great significance for the commercialization of perovskite solar cells (PSCs). However, this goal is difficult to ...achieve due to the purity of the recovered products and the easy oxidation of Sn2+. Here, a simple one‐step synthetic process to convert waste Sn–Pb solder into SnI2/PbI2 and then applied as‐prepared SnI2/PbI2 to PSCs for high additional value is adopted. During fabrication, Sn–Pb waste solder is also employed to serve as a reducing agent to reduce the Sn4+ in Sn–Pb mixed narrow perovskite precursor and hence remove the deep trap states in perovskite. The target PSCs achieved an efficiency of 21.04%, which is better than the efficiency of the device with commercial SnI2/PbI2 (20.10%). Meanwhile, the target PSC maintained an initial efficiency of 80% even after 800 h under continuous illumination, which is significantly better than commercial devices. In addition, the method achieved a recovery rate of 90.12% for Sn–Pb waste solder, with a lab‐grade purity (over 99.8%) for SnI2/PbI2, and the cost of perovskite active layer reduced to 39.81% through this recycling strategy through calculation.
Using a simple synthesis process to convert waste Sn–Pb solder into SnI2/PbI2 and apply them to perovskite solar cells (PSCs). Meanwhile, Sn–Pb waste solder can be used as a reducing agent to remove Sn4+ from the Sn–Pb mixed perovskite precursor. The target Sn–Pb mixed PSC achieved an efficiency of 21.04%.
Defects at the grain boundary, surface and interface, acting as nonradiative recombination centers, result in considerable energy loss of perovskite solar cells (PSCs). Herein, we passivated the ...defects of polycrystalline perovskite films with acetamidine halide (AAI or AABr) and identified their energy loss before and after passivation. We find that the trap state densities are 9.20 × 10
15
cm
−3
and 9.62 × 10
15
cm
−3
for AAI-treated and AABr-treated perovskite films, lower than 1.09 × 10
16
cm
−3
for the pristine film. As a result, PSCs with configuration of ITO/SnO
2
/perovskite/spiro-OMeTAD/Ag achieve a champion PCE of 22.0% with AAI treatment and 21.5% with AABr treatment, higher than 20.4% PCE for the pristine PSCs. In LED mode, the maximum electroluminescence external quantum efficiencies (EQE
EL
) are 4.06% and 3.45% for AAI and AABr passivated PSCs, respectively, higher than 0.94% for the pristine device. EQE
EL
values are 1.26%, 1.20% and 0.40% under an injection current of photocurrent for AAI, AABr and pristine PSCs suggesting that the nonradiative
V
OC
loss is 112 mV, 114 mV and 142 mV, respectively. In terms of charge transfer loss, fill factor reduction is estimated to be 6.3%, 7.0% and 7.4% for AAI, AABr and pristine films, respectively. Passivation using acetamidine halide can significantly improve the energy loss and improve stability.
We quantified non-radiative recombination loss and charge transfer loss for acetamidine halide passivated perovskite solar cells.
The rolling‐off phenomenon of device efficiency at high current density caused by quenching of luminescence in perovskite light‐emitting diodes (PeLED) is challenging to be solved. Here, ...2‐amino‐5‐iodopyrazine (AIPZ) is dissolved in a mixed solvent of chlorobenzene (CB)/isopropanol (IPA) (7:3 volume ratio) for surface post‐treatment of FAPbI3 perovskite film. The interaction of AIPZ and perovskite surface not only balances the charge injection but also passivates defects to enhance radiative recombination in PeLED. Therefore, the PeLED champion yields peak external quantum efficiency reaching 23.2% at the current density of 45 mA cm−2 with a radiance brightness of 290 W sr−1 m−2. More importantly, the rolling‐off of device efficiency is significantly reduced. The lowest rolling‐off devices can maintain 80% of peak EQE (22.1%) at a high current density of 460 mA cm−2, whereas the control device only retains 25% of the peak EQE value. This work provides an effective strategy to improve performance and reduce the EQE rolling‐off of PeLED for practical application.
The rolling‐off of device efficiency at high current density caused by quenching of luminescence in perovskite light‐emitting diodes is challenging to solve. By using 2‐amino‐5‐iodopyrazine (AIPZ) as a passivator for FAPbI3 perovskite film, this work reveals that microcrystal surface treatment plays an important role in the preparation of PeLED devices with high efficiency of over 20% and low rolling‐off simultaneously.
Two‐step‐fabricated FAPbI3‐based perovskites have attracted increasing attention because of their excellent film quality and reproducibility. However, the underlying film formation mechanism remains ...mysterious. Here, the crystallization kinetics of a benchmark FAPbI3‐based perovskite film with sequential A‐site doping of Cs+ and GA+ is revealed by in situ X‐ray scattering and first‐principles calculations. Incorporating Cs+ in the first step induces an alternative pathway from δ‐CsPbI3 to perovskite α‐phase, which is energetically more favorable than the conventional pathways from PbI2. However, pinholes are formed due to the nonuniform nucleation with sparse δ‐CsPbI3 crystals. Fortunately, incorporating GA+ in the second step can not only promote the phase transition from δ‐CsPbI3 to the perovskite α‐phase, but also eliminate pinholes via Ostwald ripening and enhanced grain boundary migration, thus boosting efficiencies of perovskite solar cells over 23%. This work demonstrates the unprecedented advantage of the two‐step process over the one‐step process, allowing a precise control of the perovskite crystallization kinetics by decoupling the crystal nucleation and growth process.
The whole crystallization pathways and mechanism of two‐step‐fabricated perovskites are unveiled by in situ grazing‐incidence wide‐angle X‐ray scattering measurements and density functional theory calculations. Sequential A‐site doping of Cs+ and GA+ is found to alter the crystallization kinetics and improves the perovskite film morphology, giving rise to device efficiency as high as 23.5%.
