The schematic diagram of different Sn-5s and I-5p antibonding strengths of FASnI3 and MASnI3 due to various bond lengths of Sn–I.
In this work, a SnO /ZnO bilayered electron transporting layer (ETL) aimed to achieve low energy loss and large open-circuit voltage (V ) for high-efficiency all-inorganic CsPbI Br perovskite solar cells (PVSCs) is introduced. The high-quality CsPbI Br film with regular crystal grains and full coverage can be realized on the SnO /ZnO surface. The higher-lying conduction band minimum of ZnO facilitates desirable cascade energy level alignment between the perovskite and SnO /ZnO bilayered ETL with superior electron extraction capability, resulting in a suppressed interfacial trap-assisted recombination with lower charge recombination rate and greater charge extraction efficiency. The as-optimized all-inorganic PVSC delivers a high V of 1.23 V and power conversion efficiency (PCE) of 14.6%, which is one of the best efficiencies reported for the Cs-based all-inorganic PVSCs to date. More importantly, decent thermal stability with only 20% PCE loss is demonstrated for the SnO /ZnO-based CsPbI Br PVSCs after being heated at 85 °C for 300 h. These findings provide important interface design insights that will be crucial to further improve the efficiency of all-inorganic PVSCs in the future.
Adding 2-phenoxyethylamine (POEA) into a CH NH PbBr precursor solution can modulate the organic-inorganic hybrid perovskite structure from bulk to layered, with a photoluminescence and electroluminescence shift from green to blue. Meanwhile, POEA can passivate the CH NH PbBr surface and help to obtain a pure CH NH PbBr phase, leading to an improvement of the external quantum efficiency to nearly 3% in CH NH PbBr LED.
In this work, both anode and cathode interfaces of p‐i‐n CH3NH3PbI3 perovskite solar cells (PVSCs) are simultaneously modified to achieve large open‐circuit voltage (Voc) and fill factor (FF) for high performance semitransparent PVSCs (ST‐PVSCs). At the anode, modified NiO serves as an efficient hole transport layer with appropriate surface property to promote the formation of smooth perovskite film with high coverage. At the cathode, a fullerene bisadduct, C60(CH2)(Ind), with a shallow lowest unoccupied molecular orbital level, is introduced to replace the commonly used phenyl‐C61‐butyric acid methyl ester (PCBM) as an alternative electron transport layer in PVSCs for better energy level matching with the conduction band of the perovskite layer. Therefore, the Voc, FF and power conversion efficiency (PCE) of the PVSCs increase from 1.05 V, 0.74 and 16.2% to 1.13 V, 0.80 and 18.1% when the PCBM is replaced by C60(CH2)(Ind). With the advantages of high Voc and FF, ST‐PVSCs are also fabricated using an ultrathin transparent Ag as cathode, showing an encouraging PCEs of 12.6% with corresponding average visible transmittance (AVT) over 20%. These are the highest PCEs reported for ST‐PVSCs with similar AVTs paving the way for using ST‐PVSCs as power generating windows.
effi ciency (PCE) of the record perovskite solar cells (PVSCs) has already reached over 20%, [ 6 ] making it a potential contender for new generation photovoltaic technology.The perovskite semiconductors can be adopted in various types of solar cell architectures including perovskite-sensitized solar cells, [ 1 ] meso-superstructured solar cells and planar heterojunction (PHJ) solar cells. [ 7,8 ] The latter one, which has a device architecture resembles that of polymer solar cells, is particularly attractive for potential commercialization due to the simplicity of the device structure, low-temperature solution processibility, as well as the potential of large-scale manufacturing using a continuous coating technique on fl exible substrates. [8][9][10][11][12][13][14] The most commonly used inverted device architecture for PHJ PVSCs is ITO/ poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS)/perovskite/ phenyl-C61-butyric acid methyl ester (PC 61 BM)/metal, in which the PEDOT:PSS and PC 61 BM serve as hole-transporting layer (HTL) and electron-transporting layer (ETL), respectively. Recent advances in optimizing the perovskite morphology and cathode interface have resulted in high PCE in the PEDOT:PSSbased PVSCs. [15][16][17][18][19][20][21][22][23] However, the open-circuit voltage ( V oc ) (0.90-0.95 V) in the PEDOT:PSS-based PVSCs is typically lower than that (≈1.05 V) obtained from meso-superstructured PVSCs due to the mismatched workfunction between PEDOT:PSS and the valence band of perovskite semiconductor. Therefore, new anode modifi cation is also important to fully unveil the potential of inverted PHJ PVSCs. [ 3,7,[24][25][26][27] Although several inorganicbased HTLs have been exploited to enhance the V oc and PCE of PHJ PVSCs, the severe surface charge recombination due to the presence of surface traps in the metal oxide limits their performance and the high temperature sintering process (>300 °C) required for preparing oxide fi lms with high crystallinity make it incompatible for roll-to-roll printing process and limits its practical applications. [ 12,[28][29][30][31] PEDOT:PSS is generally used as anode interlayer because of its solution processibility, good electrical property, low processing temperature, and commercial availability. Nevertheless,
The field of organic-inorganic hybrid perovskite light-emitting diodes (PeLEDs) has developed rapidly in recent years. Although the performance of PeLEDs continues to improve through film quality control and device optimization, little research has been dedicated to understanding the recombination dynamics in perovskite thin films. Likewise, little has been done to investigate the effects of recombination dynamics on the overall light-emitting behavior of PeLEDs. Therefore, this study investigates the recombination dynamics of CH NH PbI thin films with differing crystal sizes by measurement of fluence-dependent transient absorption dynamics and time-resolved photoluminescence. The aim is to find out the link between recombination dynamics and device behavior in PeLEDs. It is found that bimolecular and Auger recombination become more efficient as the crystal size decreases and monomolecular recombination rate is affected by the trap density of perovskite. By defining the radiative efficiency Φ(n), which relates to the monomolecular, bimolecular, and Auger recombination, the fundamental recombination properties of CH NH PbI films are discerned in quantitative terms. These findings help us to understand the light emission behavior of PeLEDs. This study takes an important step toward establishing the relationship between film structure, recombination dynamics, and device behavior for PeLEDs, thereby providing useful insights toward the design of better perovskite devices.
Highly efficient planar heterojunction perovskite solar cells (PVSCs) with dopamine (DA) semiquinone radical modified poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) (DA-PEDOT:PSS) as a hole transporting layer (HTL) were fabricated. A combination of characterization techniques were employed to investigate the effects of DA doping on the electron donating capability of DA-PEDOT:PSS, perovskite film quality and charge recombination kinetics in the solar cells. Our study shows that DA doping endows the DA-PEDOT:PSS-modified PVSCs with a higher radical content and greater perovskite to HTL charge extraction capability. In addition, the DA doping also improves work function of the HTL, increases perovskite film crystallinity, and the amino and hydroxyl groups in DA can interact with the undercoordinated Pb atoms on the perovskite crystal, reducing charge-recombination rate and increasing charge-extraction efficiency. Therefore, the DA-PEDOT:PSS-modified solar cells outperform those based on PEDOT:PSS, increasing open-circuit voltage (V oc ) and power conversion efficiency (PCE) to 1.08 V and 18.5%, respectively. Even more importantly, the efficiency of the unencapsulated DA-PEDOT:PSS-based PVSCs are well retained with only 20% PCE loss after exposure to air for 250 hours. These in-depth insights into structure and performance provide clear and novel guidelines for the design of effective HTLs to facilitate the practical application of inverted planar heterojunction PVSCs.
SummaryLow-band-gap metal halide perovskite semiconductor based on mixed Sn/Pb is a key component to realize high-efficiency tandem perovskite solar cells. However, the mixed perovskites are unstable in air due to the oxidation of Sn2+. To overcome the stability problem, we introduced N-(3-aminopropyl)-2-pyrrolidinone into the CH3NH3Sn0.5Pb0.5IxCl3-x thin film. The carbonyl group on the molecule interacts with Sn2+/Pb2+ by Lewis acid coordination, forming vertically oriented 2D layered perovskite. The 2D phase is seamlessly connected to the bulk perovskite crystal, with a lattice coherently extending across the two phases. Based on this 2D/3D hybrid structure, we assembled low-band-gap Sn-based perovskite solar cells with power conversion efficiency greater than 12%. The best device was among the most stable Sn-based organic-inorganic hybrid perovskite solar cells to date, keeping 90% of its initial performance at ambient condition without encapsulation, and more than 70% under continuous illumination in an N2-filled glovebox for over 1 month.
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