Key Material Recycling And Device Intergration Process For Sustainable Perovskite Solar Cells

Solar energy has become a promising alternative to replace fossil energy due to its unlimited availability and perfect cleanliness.Perovskite solar cell（PSC）has become a dominant one of third-generation novel thin-film solar cells by virtue of its high-performance,low-cost,process-flexibility,and compatibility with flexible substrates,and simultaneously is a hot research topic in both academia and industry.Now,the certified power conversion efficiency（PCE）of single-junction PSC has reached up to 26.1%,and the stability of single-junction PSC based on IEC 61215 test and certification standard has been more than 9000 hours.However,the future commercialization is still constrained by lead pollution and non-recycled functional layer materials.To address these issues,our work has constructed a highly efficient,stable,green and sustainable PSC by full life-cycle lead management,electrode material recycling,solvent management,functional layer optimization and full encapsulation of tin-based perovskite.The detailed researches of our work are as follows:（1）A full life-cycle material management for carbon-based perovskite solar cell（C-PSC）to immobilize and recover Pb against environmental pollution has been performed,followed by refabrication of C-PSC based on recovered materials and recycled transparent conductors from obsolete devices.Pb immobilization is first achieved by a strong coordination interaction between undercoordinated Pb ions from perovskite and a C=O bond from green pseudohalide ions（Ac^-）and a final Pb concentration reduces to 5.2 ppm from15.1 ppm.The resulting C-PSC with the structure of ITO/SnO₂/MAPbI₃/Carbon yields an enhanced efficiency to 16.63%from 12.61%.Pb from an end-of-life C-PSC is then recovered by dissolving the obsolete perovskite layer into DMF/DMSO precursor solvent,followed by replenishing a certain amount of MAI to guarantee new perovskite layer formation.The refabricated C-PSC based on recovered perovskite and recycled transparent conductor displays comparable efficiency（15.30%）to that（16.63%）of C-PSC with commercial materials.The LCOE of refabricated C-PSC is evaluated to be$0.0407/k Wh about 62%lower than fresh C-PSC（$0.107/k Wh）.（2）A facile eco-friendly process for upcycled sustainable PSC by screening the polar Pb solubilizers（N,N-dimethylformamide,DMF,dimethyl sulfoxide,DMSO and butylamine,BA）coupling with multi-function potassium iodide（KI）precipitator has been performed.DMF with strong Pb-dissolution capacity and weak coupled C=O-Pb adhesion exhibits superb separation and recovery of Pb from obsolete PSC devices.Interestingly,the KI precipitator added to the Pb-containing DMF solution not only induces the formation of high-quality PbI₂ and thus high-crystallized defect-less perovskite matrix,but also relieves the residual tensile strain stemming from lattice expansion leading to orderly lattice orientation for perovskite crystallization.As a result,the re-fabricated PSC based on recovered components（PbI₂,ITO and Ag）shows a PCE of 22.78%,about 10%higher than that（20.76%）of PSC based on fresh components.The PCE of the unencapsulated device keeps>90%of the initial value after being stored in a high humidity（RH=60～80%）environment for 1200h,stronger than that（79%）of the fresh device.（3）A simple indium tin oxide（ITO）-free and HTL-free all-carbon-electrode flexible perovskite solar cell（AC-F-PSC）with an architecture of PEN/Carbon/SnO₂/Perovskite/Carbon has been construted,which contains an anode made of a carbon-based integrator（CNT/GR）comprising carbon nanotubes and low-dose graphene,and a cathode made of the commonly used conductive carbon.The CNT/GR anode exhibits low sheet resistance,high light transmittance,and superior flexibility beyond ITO.Density functional theory calculation reveals that O atoms from GR anchored onto the interwoven CNT network have strong covalent binding capacity with bond-deficient Sn ions,inhibiting the formation of oxygen vacancies in SnO₂.Such a binding effect induces a significant reduction of the conduction band minimum of SnO₂,yielding favorable energy level alignment for carrier transport at the SnO₂/perovskite interface.Further,a heat-pressing approach as a tiny trick is used to fill the gaps at the perovskite/carbon cathode interface.The resulting AC-F-PSC device attains an enhanced efficiency to 13.14%from 10.45%,with superior mechanical flexibility.（4）A full-encapsulation strategy for air-stable tin-based perovskite film by N,N-methylenebisacrylamide（MBA）in situ polymerizing internal encapsulation and Polymethyl Methacrylate（PMMA）external encapsulation has been developed.The fully-encapsulated tin-based perovskite film appears no obvious decomposition after being aged in air for 4 days,more stable than the unencapsulated film（complete decomposition）.The uniform polymer internal encapsulation layer constructed by cross-linkable MBA monomers in tin-based perovskite not only can inhibit the oxidation of Sn²⁺by strong coordination interaction between C=O from MBA and Sn²⁺in tin-based perovskite,but also can inhibit the formation of I-vacancy defects by hydrogen bond interaction between N-H from MBA and I in tin-based perovskite.As a result,the inverted device with an architecture of ITO/PEDOT/Tin-perovskite/PCBM/Ag achieves an enhanced efficiency to 12.49%from 9.85%,with excellent air stability,i.e.>80%of the initial efficiency value after storage in air environment for 1200h.