Bifunctional SnO₂ Colloid Offers No Annealing Effect Compact Layer and Mesoporous Scaffold for Efficient Perovskite Solar Cells

Abstract

SnO2 compact layer (c‐SnO2) frequently suffers from degradation in high temperature processes (HTP) such as crack, worse interfacial contact, and electrical properties, that is, annealing effect. To solve this problem, a kind of bifunctional SnO2 colloid is developed by using small molecular oxalate whose organic components can be removed clearly at a low temperature process (LTP). The c‐SnO2 and SnO2 mesoporous layer (m‐SnO2) derived from the fresh and aged sols with the same colloid show no annealing effect, decreasing oxygen vacancy, and adsorbing water on increasing annealing temperature. The champion devices of LTP and HTP SnO2 planar perovskite solar cells (PSCs) achieve, respectively, stabilized photoelectric conversion efficiencies (PCEs) of 20.74% and 20.70%. In contrast, the performance of champion devices of their mesoporous counterparts is significantly improved, showing nearly hysteresis free character with stabilized PCEs of 22.40% and 22.37%, respectively. The inclusion of m‐SnO2 plays a role of an energy bridge, improving electrons collection efficiency, which is supported by photoluminescence and transient photoluminescence characterizations. HTP SnO2 mesoporous PSCs can preserve 97.6% and 80% of their initial PCEs after aging for 25 weeks and 8‐h irradiated/16‐h dark cycle within 104 h. The high stability of HTP SnO2 PSCs may ascribe to low oxygen vacancy and adsorbed water of HTP SnO2.

Recent Developments in Upscalable Printing Techniques for Perovskite Solar Cells

“…Similarly, for the conventional n-i-p structured mesoporous PSCs, SnO 2 scaffolds have been utilized as ETLs, which delivered a PCE of over 22%. [50,51] Also, inverted p-i-n structured mesoporous PSCs have been reported to employ mesoporous NiO x and CuGaO 2 HTLs that effectively extract holes from perovskite due to the increased contact area of the perovskite/HTL, resulting PCE approximately 20%. [52,53]…”

Carrier Management via Integrating InP Quantum Dots into Electron Transport Layer for Efficient Perovskite Solar Cells

“…Fang et al incorporated cobalt chloride hexahydrate (CoCl 2 ·6H 2 O) into the SnO 2 ETL films, which exhibited favorable energy level alignment and better charge extraction . On the other hand, surface passivation with small organic molecular and inorganic salts has been used to solve issues originating from the ETL/perovskite interface. − Padture et al deposited an iodine-terminated self-assembled monolayer (I-SAM) between the ETL and the perovskite layer, which created anchoring O–Si bonds with surface −OH groups of SnO 2 and reduced trap states . Kong et al designed an interlayer with coherent features between SnO 2 and perovskite to passivate interfacial defects.…”

Highly Efficient Large-Area Flexible Perovskite Solar Cells Containing Tin Oxide Vertical Nanopillars without Oxygen Vacancies

“…The PSCs with the (40BL + 125NP) SnO 2 had a lower V OC value of 1.00 V. Mott–Schottky characterization (Figure S13) showed that the built-in voltage ( V bi ) of the PSCs with the (40BL + 125NP) SnO 2 is 0.55 V, smaller than that for the spin-coated and (40BL + 125NP)-Oxy SnO 2 (0.64 and 0.66 V, respectively). It illuminates that the lower V OC value can be ascribed to oxygen vacancies in the (40BL + 125NP) SnO 2 trap charges, increase internal electric fields, and then cause energy loss of transporting charges. ,, …”