A solution-processed pillar[5]arene-based small molecule cathode buffer layer for efficient planar perovskite solar cells

Abstract

A room-temperature solution-processed pillar[5]arene-based small molecule material, termed C3, has been designed, synthesized, and incorporated between a conventional PCBM electron transport layer (ETL) and a metal electrode to function as a single-layer cathode buffer layer (CBL) for efficient planar p-i-n perovskite solar cells (PVSCs). It has been found that C3 has a work function tunneling effect, which can decrease the work function of the Ag electrode; therefore, introduction of C3 successfully enhances the interface contact and reduces the interface barriers, which usually exist between fullerene derivatives and metal electrodes. It was also found that the C3 capping layer could improve the surface quality of PCBM, forming a smooth, dense and pinhole-free morphology with fewer surface defects. Thus, C3 can modify the interface between PCBM and Ag, enhance the diode properties of devices and facilitate electron transport through the devices; therefore, it is a very promising CBL material for PVSCs. A device with a hybrid PCBM ETL and a single cathode buffer layer of C3 exhibited a high power conversion efficiency (PCE) of 17.42% with negligible hysteresis, which was dramatically higher than that of a device based on a pure PCBM ETL. With the major advantages of a low-temperature solution process and interface modification, the excellent PCE of PVSCs on flexible substrates can exceed 13%. These results demonstrate that solution-processed pillar[5]arene-based small molecule materials can serve as high performance CBLs in PVSCs.

Efficient and Stable Nonfullerene‐Graded Heterojunction Inverted Perovskite Solar Cells with Inorganic Ga2O3 Tunneling Protective Nanolayer

“…Some organic materials, including C3, solution‐processed pillar[5]arene‐based small molecule material(C3), amino‐functionalized polymer (PN4N), bathocuproine (BCP), solution‐processed perylene–diimide (PDINO), 4,7‐diphenyl‐1,10‐phenanthroline (Bphen), titanium (diisopropoxide) bis(2,4‐pentanedionate (TIPD), (11‐mercaptoundecyl)‐ N , N , N ‐trimethylammonium bromide (MUTAB), and solution‐processed carboxylic potassium salt (F‐R‐COOK), have been proven to be cathode buffer layers (CBLs) for p–i–n PSCs. However, these organic materials cannot effectively hinder metal electrode like Ag from diffuse in to perovskite and prevent the ingress of moisture toward the perovskite . On the other hand, inorganic metal oxides, such as TiO 2 , ZnO, ZnO:Al, and SnO 2 are excellent CBLs for protecting perovskite and improve the cell stability .…”

Zwitterions for Organic/Perovskite Solar Cells, Light‐Emitting Devices, and Lithium Ion Batteries: Recent Progress and Perspectives

“…[240][241][242][243][244] Second, interfacial materials can enhance the electrode selectivity and charge transportation in the devices. [175][176][177][178][179][180] In fact, the photovoltaic parameters (V OC , J SC , and FF) depend on the quantity of builtin electric field, which is governed by the WF difference of anode-cathode electrodes. [246][247][248] Lastly, interfacial materials also have a significant impact on the morphology and hence the stability of the electronic devices.…”

“…FF and V OC were enhanced from 0.53 to 0.73 and 0.91 to 1.01 V, subsequently, whereas the J SC remained almost the same (17.71 mA cm −2 ) ( Table 3). 2019, 9,1803354 [179] www.advancedsciencenews.com of almost 30 min at 65 °C), followed by the deposition of the perovskite film on PEDOT:PSS surface. This little increase in PbI 2 led to a reduction in the charge recombination.…”

“…[178] The inverted PVSC device constructed with the configuration of ITO/NiO x /Perovskite layer/PC 61 BM/Phen-I/Ag by inserting Phen-I ZEI realized a high PCE of 18.13%. [179] In addition to this, they also used a film of crosslinked molecule X1 (5,5′-bis(9-(4-vinylbenzyl)-9H-carbazol-2yl)-2,2′-bithiophene) to replace PEDOT:PSS as anode interlayer and to reduce V OC losses. High values of photovoltaic parameters were obtained (V OC of 1.13 V, J SC of 20.51 mA cm −2 , and an FF of 78.54%).…”

“…Phen-I possessed deep HOMO level, which facilitated to block the holes and avoided the unwanted charges moving toward cathode, minimizing the recombination of holes and electrons. [179] Adv. [178] These values were significantly higher than control device parameters (PCE of 10.7%, with a V OC of 1.10 V, a J SC of 18.15 mA cm −2 , and an FF of 53.56%).…”