Incorporating Solution-Processed Mesoporous WO₃ as an Interfacial Cathode Buffer Layer for Photovoltaic Applications

Abstract

Dextran-templating hydrothermal synthesis of monoclinic WO3 exhibits excellent specific surface area of ∼110 m2/g and a monomodal pore distribution with an average pore diameter of ∼20 nm. Dextran plays a crucial role in generating porosity on WO3. The role of supporting dextran has been investigated and found to be crucial to tune the surface area, porosity, and morphology. The photoluminescence and X-ray photoelectron spectroscopy studies reveal the existence of oxygen vacancies in substoichiometric WO3, which creates localized defect states in WO3 as synthesized through this templating method. The highly mesoporous WO3 has been further explored as an interfacial cathode buffer layer (CBL) in dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs). A significantly enhanced photoconversion efficiency has boosted up the performance of the counter electrode used in traditional DSSC (as platinum) and PSC (as carbon) devices by ∼48 and ∼29%, respectively. The electrochemical impedance and incident photon to current conversion efficiency (IPCE) studies were also analyzed in order to understand the catalytic behavior of the WO3 interfacial CBL for both DSSCs and PSCs, respectively. The much higher surface area of WO3 enables rapid electron hopping mechanism, which further benefits for higher electron mobility, resulting in higher short circuit current. Through this study, we were able to unequivocally establish the importance of buffer layer incorporation, which can further help to integrate the DSSC and PSC devices toward more stable, reliable, and enhanced efficiency-generating devices. In spite of this, using WO3 constitutes an important step toward the efficiency improvement of the devices for futuristic photoelectrochromic or self-powered switchable glazing for low-energy adaptive building integration.

Perceiving the temperature coefficients of carbon-based perovskite solar cells

“…R rec is charge transfer resistance at the perovskite/carbon interface. 59 In Fig. 5d, the large parabola in the high-frequency region implies higher transportation and exchange resistance from perovskite to carbon counter electrode, which will influence the fill factor as reflected from J-V characterization.…”

“…influence of surrounding moisture and air, although the devices were kept inside a chamber of fixed temperature. It was suggested that excess PbI 2 in MAPbI 3 could help to passivate defects at surfaces, and grain boundaries and a small amount of residual PbI 2 in perovskite supports to reduce charge recombination and improves the V OC and FF 59. As a result, the devices do not lose its V OC under thermal stress, indicating the PCE loss is mainly restricted with the J SC .…”

Porous Tungsten Oxide: Recent Advances in Design, Synthesis, and Applications

“…The porous WO 3 boosted the J sc of perovskite cells to 24.21 mA cm À 2 which is higher than that of nonporous WO 3 (20.15 mA cm À 2 ). [67] A combination of photochemical and electrochemical properties of WO 3 makes it an efficient photoelectrochemical catalyst. These catalysts use photons to excite surface molecules that are then used in a reaction that generates energy.…”

Perovskite Solar Cells for BIPV Application: A Review

“…An effort has been executed to find a suitable medium between high electrical efficiency and a high AVT, as shown in Figure 5. The thickness and structure of the mesoporous layer create an impact on PSC performance [150]. The optical transparency of the other interlayers and the semi-transparent electrode of PSC influence to archive high PCE [151].…”