The Structural Design Of NiO Hole Transport Layer And Construction Of Wearable Photovoltaic Devices

Recently,perovskite solar cells（PSCs）have been intensively investigated due to their superior optical properties,facile preparation and low cost,which can be comparable to Si-based solar cells.Among the developed structures,inverted P-I-N devices based on p-types inorganic semiconductor materials（such as NiO）,which exhibit the better stability and lower J-V hysteresis,have received increasing attention.However,the conventional solution-processed NiO nanocrystal film are easy to agglomerate and cause many defects（discontinuous surface/interface of film,high resistance,etc.）.This would lead to the severe nonradiative recombination loss at NiO/Perovskite interface,and significantly limits the device performance.Hence,design a new type of high-quality NiO film as efficient hole-transporting layers（HTLs）is critical for the development of P-I-N devices.Besides,research indicates that the flexibility and intelligent wearability of optoelectronic devices will be the important development direction in the future.And it is of great scientific significance and application prospect to develop flexible intelligent wearable optoelectronic devices.In summary,this work focuses on the design of NiO HTLs and fabrication of wearable PSCs.First,we precisely regulate the multidimensional nanostructure of NiO to realize the functional design of HTLs,thus improving the device performance.Based on these,we then develop a new type of composite fabric electrode,and investigate the preparation of wearable PSCs based on such fabric-based electrode in detail.The main research work is as follows:（1）Aiming at the key issues of intrinsic poor conductivity of conventional NiO nanocrystal film,two types of 1D nanostructure（NiO nanotube,Zn:NiO nanorod）have been developed as novel HTLs.The study finds that the optimization of aspect ratio or Zn doping concentration of such 1D NiO can greatly improve its conductivity and charge extraction ability,and provide highway for interfacial photogenerated charge separation/transfer.Benefitting from suppressed nonradiative recombination loss,all the devices based on these 1D NiO HTLs exhibit the improved open-circuit voltage,and the champion efficiency are 18.77%and 19.83%respectively.Besides,the J-V hysteresis is also optimized.This work demonstrates the great significance of 1D inorganic semiconductor materials in developing high-performance P-I-N device.（2）Aiming at the key issues of defect-rich and severe charge recombination at NiO/Perosvkite interface,the mesoporous network structure consisting of NiO nanosheet was developed as HTLs.The results indicate that such unique structure could fabricate the deposition of high-quality perovskite film,passivate the interfacial defect,and even decrease the charge transfer resistance.To further improve the device performance,the regulator was additionally introduced to form ordered nanowall arrays,and combined with the synergistic modification of NiO/perovskite interface by diethanolamine,the efficiency of 19.16%with the high fill factor of over 80%was realized.Besides,benefitting from the construction of mesoporous structure,the degradation process of perovskite layer caused by air components（H₂O,O₂,etc.）is also effectively slowed down.Hence,the device can maintain the 80%of initial PCEs after storing 500 h in 50-70%RH%,suggesting the better stability.（3）Aiming at the key issues of inferior performance caused by undesirable hole extraction efficiency or light harvesting efficiency,the NiO_x/C heterojunction sphere and hollow Cu:NiO_xsphere was designed as functional HTLs respectively.Herein,NiO_x/C sphere could significantly enhance the interfacial built-in-electric field,and promote the fast hole extraction/transport,which is attributed to the better hole conductivity（3-4 times than conventional NiO nanocrystal）.More importantly,the interfacial energy levels are graded and the energy transfer loss caused by energy level barrier is also reduced,so the high efficiency of 19.51%is achieved.For the hollow Cu:NiO_xsphere,it focuses on optimizing the optical field distribution,boosting the light harvesting and reducing light loss.Therefore,the high short-circuit current density of 24.41 m A/cm² is realized,which close to the 91%of Shockley-Queisser theoretical value.And the efficiency of device is also boosted up to 20.40%.This work indicates the design of NiO HTLs structure is the effective approach to fabricate efficient P-I-N device.（4）In view of the fact that conventional ITO/PET substrates cannot meet the future development needs of wearable devices,by integrating the characteristic subject of textile science and engineering,we demonstrate a new type of NiO/graphite paper/fabric composite electrode,and initially construct the wearable fabric-based PSCs.As a result,the composite fabric electrode exhibits the advantages of simple-fabrication,low cost,and good complex deformability and stretchability,better than that of ITO/PET electrode.Besides,by using the combined strategy of PMMA interface passivation and PS doping,the key issues of poor perovskite film deposited on fabric electrode has been addressed.Finally,a consideration PCE of 2.27%was achieved.Moreover,this fabric-based wearable PSCs also exhibits the mechanical stability,which can still work stably without failure after a large deformation or a certain stretch.after simple packaging,the device also has certain washing capacity.Overall,this can greatly expand the scope of its application,and provide a reference for the future development of wearable perovskite photovoltaic devices...