| Recently,perovskite solar cells(pero-SCs)and organic solar cells(OSCs)have achieved rapid progress with certified power conversion efficiencies(PCEs)over 25%and 18%,respectively.Nevertheless,owing to the presence of serious non-radiative recombination losses,the best research-cell PCEs are still below the theoretical limit defined by the Shockley-Queisser theory,which imposes constraints on the further development of pero-SCs and OSCs.Firstly,the prevalent defects in pero-SCs,which are the source of notorious charge non-radiative recombination and ion migration,lead to poor PCE and stability.The conventional passivation strategies exhibit a high dependence on device areas,which limits the application of these strategies in large-area devices.Secondly,on switching to high-boiling-point green solvents,which are required for industrial development,the active layer of OSCs usually suffers from serious phase separation and unfavorable morphology.This leads to serious non-radiative recombination losses and a notable drop in the PCEs.Therefore,for industrial development of the pero-SCs and OSCs,we develop intrinsic strategies with a weak scale dependence to suppress the non-radiative recombination loss in pero-SCs and green-solvents-processed OSCs.The main results are as follows.(1)Two n-type organic molecules with hydrogen-transfer properties for the doping of bulk perovskite aimed at regulating its electronic states were developed.The doping effect could reduce the electron trap density,increase the electron concentration of the bulk perovskite,and simultaneously improve the surface electronic contact.When the DMBI-2Th-I-doped perovskite is used in planar p-i-n pero-SCs,the nonradiative recombination is significantly suppressed.As a result,the photovoltaic performance improved significantly,as evidenced by an excellent PCE of 20.90%and a robust ambient stability even under high relative humidity.(2)We revealed a dielectric-screening-enhancement effect for perovskite defects by using high dielectric constant organic semiconductors with finely tuned molecular structures from the atoms level.Our method produced various perovskite films with high dielectric constant values,reduced charge capture regions,suppressed ion migration,and it provides an efficient charge transport pathway for suppressing non-radiative recombination beyond the passivation effect.The resulting pero-SCs(device area of 0.062 cm2)showed a promising PCE of 23.35%with a high open-circuit voltage(1.22 V);and the 1-cm2 pero-SCs maintained an excellent PCE(22.46%),showing feasibility for scalable fabrication.In addition,these pero-SCs exhibited robust operational and thermal stabilities.(3)Organic semiconductor guest molecules(BT20,BTO,BT40)with different numbers of ethylene glycol repeating unit side chains were developed.Based on these guest molecules,the host-guest active layer material design strategy of OSCs was proposed.In addition,the structure-activity relationship between the guest molecular structure and the crystallization kinetics of the active layer in green solvent was clarified.It was found that the guest molecule design needs to take into account the balance between molecular assembly ability and molecular stacking steric hindrance.(4)Based on the organic semiconductor guest molecule BTO,the guest-assisted assembly strategy was developed to manipulate the compatibility,solubility,and molecularorganization of active layer materials when transferring the processing from low-boilingpoint chloroform to high-boiling-point green solvent p-xylene(PX).Benefiting from the suppressed non-radiative recombination loss,the resulting OSCs(device area of 0.062 cm2)exhibited a record PCE of 17.48%.In addition,the high-boiling-point green solvent PX also enabled us to deposit a uniform large-area module(device area of 36 cm2)with a high efficiency of over 14%.Importantly,the strong molecular interaction between the host and guest molecules also enhanced the operational stability of the devices. |
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