Promoting the Hole Extraction with Co₃O₄ Nanomaterials for Efficient Carbon‐Based CsPbI₂Br Perovskite Solar Cells

Abstract

Carbon‐based perovskite solar cells (PSCs) have gathered much attention due to their excellent thermal stability and low cost. However, the typically used hole‐conductor‐free PSCs based on carbon electrodes show the worst performance due to the serious charge recombination at the perovskite/carbon interface. In this work, the efficient and stable carbon‐based CsPbI2Br PSCs using Co3O4 as the hole transport material (HTM) are fabricated and their photoelectric properties are systematically investigated. It is found that the Co3O4 inorganic HTM effectively promotes photo‐generated charges separation and extraction, and suppresses charge recombination at the CsPbI2Br/carbon electrode interface, resulting in the improved photovoltaic performance. At the optimal Co3O4 concentration, the carbon‐based CsPbI2Br PSCs achieve the maximum efficiency of 11.21% with a negligible J–V hysteresis. This work provides a novel strategy to fabricate efficient and stable all‐inorganic PSCs.

All‐Inorganic CsPbX3 Perovskite Solar Cells: Progress and Prospects

“…Despite the rapid progress,the PCE achieved to date for the CsPbI 2 Br solar cells is still too low,l eaving considerable room for further improvement. [177,178] Foraband gap of 1.9 eV,t he maximum voltage that can be theoretically extracted from non-concentrated standard sunlight is 1.589 V; [179] we are still af ew hundred mV below this.N onradiative recombination, mismatched energy levels between HaP and (selective) charge extraction layers,p oor intrinsic photoluminescence (PL) quantum efficiency and shorting (which is more likely where the morphology of the HaP layer is poor) can all contribute to the present losses. [180] Nonradiative recombination can be influenced by the perovskite interfaces with other cell components in several ways:1 )by recombination at interface states (from the HaP,f rom the other component or due to interaction between both phases; 2) by modifying the rate of charge extraction (slower extraction favors more recombination-both radiative and nonradiative);3)if, for example,the conduction band of the HaP is lower than that of the ETL, this will reduce the rate of electron extraction (similarly if the valence band of the HaP is higher than that of the HTL);4 )the opposite of (3), conduction band of the HaP is higher than that of the ETL, in which case ab arrier is formed due to the band mismatch and this is (in as imple picture) reflected as al oss in energy (therefore V OC )equal to the size of the barrier.…”

Inorganic CsPbIBr2‐Based Perovskite Solar Cells: Fabrication Technique Modification and Efficiency Improvement

“…However, CsPbI 3 , with a narrower bandgap of ≈1.73 eV, faces an adverse fabrication condition of high temperature (>300 °C), which is necessary to obtain our desired α‐phase perovskite . CsPbI 2 Br, a promising perovskite material for all‐inorganic HPSCs, has been reported by many researchers . However, the device stability of CsPbI 2 Br‐based HPSCs is still a challenging task to overcome.…”

Anorganische CsPbX3‐Perowskit‐Solarzellen: Fortschritte und Perspektiven

“…[177,178] Bei einer Bandlücke von 1.9 eV ist die maximale Spannung,d ie theoretisch aus nicht-konzentriertem Standard-Sonnenlicht gewonnen werden kann, 1.589 V. [179] Aktuelle PSCs liegen einige hundert mV unter diesem theoretischen Wert. [177,178] Bei einer Bandlücke von 1.9 eV ist die maximale Spannung,d ie theoretisch aus nicht-konzentriertem Standard-Sonnenlicht gewonnen werden kann, 1.589 V. [179] Aktuelle PSCs liegen einige hundert mV unter diesem theoretischen Wert.…”

“…Tr otz des rasanten Fortschritts sind die bisher erreichten PCE-Werte der CsPbI 2 Br-Solarzellen noch zu niedrig und lassen deutlichen Spielraum fürw eitere Verbesserungen. [177,178] Bei einer Bandlücke von 1.9 eV ist die maximale Spannung,d ie theoretisch aus nicht-konzentriertem Standard-Sonnenlicht gewonnen werden kann, 1.589 V. [179] Aktuelle PSCs liegen einige hundert mV unter diesem theoretischen Wert. Strahlungslose Rekombination, ungleiche Energieniveaus zwischen HaP und (selektiven) Ladungsextraktionsschichten, schlechte intrinsische PL-Quanteneffizienz und Kurzschlüsse (die wahrscheinlicher auftreten je schlechter die Morphologie der HaP-Schicht ist) sind Faktoren, die zu den gegenwärtigen Leistungsverlusten beitragen kçnnen.…”