•Ag2S/PANI shows an extra light harvesting and improved catalytic performance.•The both-side efficiency shows 130% of that of the conventional structured DSSC.•The rear-illuminated efficiency reaches 94.0% of that from front-side irradiation.•DSSCs with Ag2S/PANI show enhanced electron transport and recombination properties.Ag2S quantum dots (QDs) were employed as an interfacial layer between polymer electrolyte and transparent polyaniline counter electrode (PANI CE) in bifacial dye-sensitized solar cells (DSSCs). The Ag2S QDs film, which was prepared by successive ionic layer adsorption and reaction (SILAR) could deliver an extra visible light harvesting and enhance the catalytic performance of PANI CE, leading to increased photo-generated electrons and suppressed interfacial recombination. The device performances have been significantly improved as compared to the controlled DSSC without Ag2S QDs interfacial layer (QDIL). An optimal power conversion efficiency of 6.50% was achieved in the Ag2S QDILs based solid-state bifacial DSSC with 2 SILAR cycles, which was comparable to the highest reported efficiency of 7–8% for solid-state DSSCs, and was almost 130% of the conventional structured DSSC without Ag2S QDIL (5.02%). Electrochemical and electron transport/recombination performances have also been demonstrated for this type of device. The results also highlight the general importance of light-active QDs interfacial layer in transparent cathode for other kind of devices.Download high-res image (541KB)Download full-size image

•Introducing PVP to PANI improves the electrochemical properties of transparent CEs.•The rear-illuminated efficiency of DSSC reaches 85.5% of that from front side.•An optimal efficiency of 5.81% is achieved under illumination from both sides.•DSSCs based on PVP/PANI CEs exhibit better durability than that based on Pt CEs.We synthesized Poly (vinyl pyrrolidone) (PVP)/polyaniline (PANI) nanocomposites and applied them as transparent counter electrode (CE) for bifacial quasi-solid-state dye-sensitized solar cells (DSSCs). PVP surrounded with aniline acted as efficient steric stabilizer in the polymerization process. Moreover, the present of PVP in PANI CE facilitated the generation of active reaction-sites in the interface between counter electrode and electrolyte and further reduced the electron recombination. The DSSC fabricated with PVP (4 wt%)/PANI CE exhibited improved power conversion efficiency up to 5.45%, which was comparable to that of DSSC assembled with Pt CE (5.57%). In the case of rear-illumination, the PVP (4 wt%)/PANI based DSSC showed an efficiency of 4.66%, which was 85.5% of the efficiency obtained from front illumination and much higher than that of DSSC with Pt CE (1.14%). The bifacial DSSC with PVP/PANI counter electrode showed an optimal power efficiency of 5.81% under illumination from both front and rear sides, which is higher than that of Pt based DSSC (5.70%) under the same condition. Long-term stability tests indicated that the photovoltaic device with PVP/PANI counter electrode exhibited an enhanced durability than that of DSSC assembled with Pt CE.

•A novel cobaltosic oxide-modified magnetic agarose electrolyte.•Magnetic field–induced ordered microstructure and increased ionic conductivity.•Improved recombination process and good long-term stability of DSSCs after magnetic field treatment.•Better photovoltaic performance of the Co3O4-modified DSSC than that of NiO-modified DSSC under magnetic field treatment.Agarose–based electrolyte containing magnetic Co3O4 nanoparticles is studied for quasi–solid–state dye–sensitized solar cells (DSSCs) under external magnetic field treatment. SEM studies reveal the existence of oriented microstructure in Co3O4–modified agarose electrolyte film under proper magnetic field intensity. The formation mechanism of this ordered structure induced by magnetic field is analyzed. The impedance analysis shows that the ionic conductivity of Co3O4–modified agarose electrolyte is obviously increased by applying magnetic field intensity of 25 mT. Improved electron recombination process and photoelectric performance are observed in DSSCs under certain magnetic field treatment by electrochemical impedance spectra (EIS) and photovoltaic studies. The DSSC treated with magnetic field can maintain the efficiency unchanged for 434 hours without sealing. This is attributed to the high ionic conductivity and improved electron transfer process in DSSC resulting from the magnetic field treatment. Comparison of photovoltaic performances for Co3O4 and NiO modified DSSCs under 25 mT magnetic field treatment shows that Co3O4-modified DSSC exhibits higher energy conversion efficiency than that of NiO-modified one at the same condition.