Groups-dependent phosphines as the organic redox for point defects elimination in hybrid perovskite solar cells

Lead(Pb)^(0) and iodine(I)^(0) point defects generated during perovskite solar cell(PSC)fabrication and photoconversion form deep band energy levels as the carriers’recombination centers.These defects not only deteriorate device efficiency,but also facilitate chemical degradation with ion migration,resulting in restricted device lifetime.Herein,we present a novel type of phosphines as the point defects stabilizer for hybrid perovskite solar cells with enhanced performances.Three phosphines with varied side groups of tributyl,trioctyl and triphenyl are exampled as the dopants in perovskite films.The group dependent redox properties were observed in the perovskite film,dependent on their molecular weights and steric hinderances of phosphines.The partially oxidized tributyl phosphine(TBUP)with additional tributyl phosphine oxides(TBPO)is efficient in reduction of lead(Pb)^(0) and iodine(I)^(0) concentrations during the device fabrication and operation.The device with TBUP-TBPO pair showed enhanced power conversion efficiency(PCE)to 20.48% and maintain 91.7% of their initial PCEs after 500 h at 65℃ thermal annealing.Thus,this work presents an efficient route of utilize the phosphine species to reduce point defects in the perovskite film,which promoting further development of novel phosphorous additives with defects stabilization,interface passivation and encapsulation for low-cost solution processed PSCs.

Ultrafast-laser-treated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)electrodes with enhanced conductivity and transparency for semitransparent perovskite solar cells

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)is an important organic electrode for solution-processed low-cost electronic devices.However,it requires doping and post-solvent treatment to improve its conductivity,and the chemicals used for such treatments may affect the device fabrication process.In this study,we developed a novel route for exploiting ultrafast lasers(femtosecond and picosecond laser)to simultaneously enhance the conductivity and transparency of PEDOT:PSS films and fabricate patterned solution-processed electrodes for electronic devices.The conductivity of the PEDOT:PSS film was improved by three orders of magnitude(from 3.1 to 1024 S·cm^(–1)),and high transparency of up to 88.5%(average visible transmittance,AVT)was achieved.Raman and depthprofiling X-ray photoelectron spectroscopy revealed that the oxidation level of PEDOT was enhanced,thereby increasing the carrier concentration.The surface PSS content also decreased,which is beneficial to the carrier mobility,resulting in significantly enhanced electrical conductivity.Further,we fabricated semitransparent perovskite solar cells using the as-made PEDOT:PSS as the transparent top electrodes,and a power conversion efficiency of 7.39%was achieved with 22.63%AVT.Thus,the proposed route for synthesizing conductive and transparent electrodes is promising for vacuum and doping-free electronics.

In-situ monitored chemical bath deposition of planar NiO x layer for inverted perovskite solar cell with enhanced efficiency

As a convenient,low-cost and up-scalable solution route,chemical bath deposition(CBD)has exhibited impressive advantages in fabricating electron transporting materials like SnO_(2),achieving record efficien-cies for regular n-i-p perovskite solar cells(PSCs).However,for the hysteresis-free and potentially more stable inverted p-i-n PSCs,CBD processing is rarely studied to improve the device performance.In this work,we first present a CBD planar NiO x film as the efficient hole transport layer for the inverted per-ovskite solar cells(IPSCs).The morphologies and semiconducting properties of the NiO x film can be ad-justed by varying the concentration of[Ni(H 2 O)x(NH 3)6-x]2+cation via in-situ monitoring of the CBD re-action process.The characterizations of ultraviolet photoelectron spectroscopy,transient absorption spec-troscopy,time-resolved photoluminescence suggest that the CBD planar NiO x film possesses enhanced conductivity and aligned energy band levels with perovskite,which benefits for the charge transport in the IPSCs.The devices based on planar NiO x at 50°C and low nickel precursor concentration achieved an enhanced efficiency from 16.14%to 18.17%.This work established an efficient CBD route to fabricate planar NiO x film for PSCs and paved the way for high performance PSCs with CBD-prepared hole transporting materials.

Surfactant-assisted doctor-blading-printed FAPbBr3 films for efficient semitransparent perovskite solar cells

Organic-inorganic hybrid perovskite solar cells have generated wide interest due to the rapid development of their photovoltaic conversion effciencies.However,the majority of the reported devices have been fabricated via spin coating with a device areaof<1 cm2.In this study,we fabricated a wide-bandgap formamidi-nium lead bromide(FAPbBr3)film using a cost-effective,high-yielding doctor-blade-coating process.The effects of different surfactants,such as I-α-phosphatidylcholine,polyoxyethylene sorbitan monooleate,sodium lauryl sulfonate,and hexadecyl trimethyl ammonium bromide,were studied during the printing process.Accompanying the optimization of the blading temperature,crystal sizes of over 10μm and large-area perovskite films of5cm×5 cm were obtained using this method.The printed FAPbBr3 solar cells exhibited a short-circuit current density of 8.22 mA/cm2,an open-circuit voltage of 1.175 V,and an efficiency of 7.29%.Subsequently,we replaced the gold with silver nanowires as the top electrode to prepare a semitransparent perovskite solar cell with an average transmittance(400-800 nm)of 25.42%,achieving a high-power efficiency of 5.11%.This study demonstrates efficient doctor-blading printing for preparing large-area FAPbBr3 films that possess high potential for applications in building integrated photovoltaics.