Preparation Of TiO₂/Polyaniline Composite Photoanode And Its Photovoltaic Performance Of QDSSC

Attributing to the excellent photo-electric property,high chemical stability and high surface activity,TiO₂ semiconductor is widely used as the photoanode for solar cell.However,as the typical TiO₂ photoanode,the morphology and chemical structure is simple and crude.The exportation of photogenerated electron is mainly dependent on the carrier diffusion,which restricts the development of device photovoltaic performance.The deficiencies of typical TiO₂ photoanode are required to be solved,including the disordered exportation and high interfacial recombination.Accordingly,the exploitation of the photoanode materials provided with high electron-transfer capability is highly required.In terms of the modulation of flat-band potential,charge carrier concentration and device impedance,we implement several modification strategies to improve the electron driving-force and carrying-capacity for TiO₂ photoanode,through ion doping,hybridization and composite-junction.In order to enhance the collection,the TiO₂nanowire array(NWA)was in-situ fabricated as electron transfer skeleton(TS)for composite photoanode.The vertical array shortens the exportation and the highly crystalline continuous nano-structure supplies a stable electron conveyor,which effectively decrease the transfer-loss.The electron transfer capability of TiO₂composite photoanodes was evaluated by CdS_xSe_1-x quantum-dots sensitized solar cell system.The TiO₂ homogeneous photoanode was prepared to increase the lattice matching,which could decrease the interfacial impedance and increase the ejection.Of which,the ultrathin TiO₂ hole-blocking layer(HBL)was prepared in chemical bath deposition(CBD)and hydrothermal method,respectively.This paper explored the motivation of Ti³⁺self-doping on electron-transfer capability for TiO₂ photoanode by the processing modulation.The introduction of Ti³⁺reduces the conduction band and increases the carrier concentration(N_D),which improves the electron driving-force and carrying-capacity for photoanode.Of the TiO₂ homo-photoanode,the PBS exhibited a larger electron transfer-capability.The device performance with PBS was improved significiantly:the PCE was 7.54%,the J_sc was 18.93 mA/cm²,V_oc was 0.779V and FF was 51.1%.The conduction-band stair founded by HBL and TS influence the build-in potential of photoanode.The construction of TiO₂/n-type PANI heterogeneous photoanode was an effective approach to increase the driving force for photo-electron exportation.Using the aprotic ionic-liquid 1-ethyl-3-methyl-imidazolium ethylsulfate([EMIM]⁺[EtSO₄]^-)as dophant,the n-type PANI HBLs in constant potential and current system(AIL-PA_cp,AIL-PA_cc)were fabricated through a facial one-pot square-wave electro-polymerization method.The TiO₂heterogeneous photoanode was obtained by n-type modified PANI HBL with in-situ growing TiO₂ NWA TS.Compared with the homo-structure,the heterogeneous photoanode supplied a stable and enhanced driving force,which suppressed the accumulation during exportation and improved the diffusion length.Of which,the device performance with TiO₂/AIL-PA_cp exhibited the enhanced performance,PCE for 10.50%,J_sc for 21.59 mA·cm^-2,V_oc for 0.869 V and FF for56.1%.To further increase the electron carrying capacity of composite photoanode and improve the charge-carrier concentration,the TiO₂/hybrid n-type PANI photoanode was established,including the TiO₂-[EMIM]⁺hybrid n-type PANI as HBL and in-situ growing TiO₂ NWA as TS.Profiting from the weak dispersion force between carbon-rings of AIL-PA molecule as well as the controllable dehydra-condensation property of Ti hydroxyl-complex,the hybrid n-type PANI was prepared by the infiltration of Ti complex and the doping of[EMIM]⁺in CBD and electro-adsorption,respectively.The hybrid PANI layers were fabricated in constant potential and current system((TiO₂+AIL)-PA_cp and(TiO₂+AIL)-PA_cc).The TiO₂/hybrid n-type PANI photoanode was obtained byhybrid PANI HBL with in-situ growing TiO₂ NWA TS.As for the hybridization,the bonding of Ti-N improves the electron density of p-?conjugation,as well as the doping of[EMIM]⁺polarizes the deviation of electron cloud.Accordingly,the electron-transfer capability of TiO₂/(TiO₂+AIL)-PA photo-anode increased and charge-transfer resistance of assembled device decreased significiantly,and the device PCE increased.The device performance with TiO₂/(TiO₂+AIL)-PA_cp exhibited the enhanced performance,PCE for 11.18%,J_sc for 25.00mA·cm^-2,V_oc for 0.815 V and FF for 54.9%.