| 1. |
- Lin, Yuanbao, et al.
(författare)
-
18.73% efficient and stable inverted organic photovoltaics featuring a hybrid hole-extraction layer
- 2023
-
Ingår i: Materials Horizons. - : Royal Society of Chemistry (RSC). - 2051-6355 .- 2051-6347. ; 10:4, s. 1292-1300
-
Tidskriftsartikel (refereegranskat)abstract
- Developing efficient and stable organic photovoltaics (OPVs) is crucial for the technology's commercial success. However, combining these key attributes remains challenging. Herein, we incorporate the small molecule 2-((3,6-dibromo-9H-carbazol-9-yl)ethyl)phosphonic acid (Br-2PACz) between the bulk-heterojunction (BHJ) and a 7 nm-thin layer of MoO3 in inverted OPVs, and study its effects on the cell performance. We find that the Br-2PACz/MoO3 hole-extraction layer (HEL) boosts the cell's power conversion efficiency (PCE) from 17.36% to 18.73% (uncertified), making them the most efficient inverted OPVs to date. The factors responsible for this improvement include enhanced charge transport, reduced carrier recombination, and favourable vertical phase separation of donor and acceptor components in the BHJ. The Br-2PACz/MoO3-based OPVs exhibit higher operational stability under continuous illumination and thermal annealing (80 degrees C). The T-80 lifetime of OPVs featuring Br-2PACz/MoO3 - taken as the time over which the cell's PCE reduces to 80% of its initial value - increases compared to MoO3-only cells from 297 to 615 h upon illumination and from 731 to 1064 h upon continuous heating. Elemental analysis of the BHJs reveals the enhanced stability to originate from the partially suppressed diffusion of Mo ions into the BHJ and the favourable distribution of the donor and acceptor components induced by the Br-2PACz.
|
|
| 2. |
- Lin, Yuanbao, et al.
(författare)
-
18.9% Efficient Organic Solar Cells Based on n-Doped Bulk-Heterojunction and Halogen-Substituted Self-Assembled Monolayers as Hole Extracting Interlayers
- 2022
-
Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6840 .- 1614-6832. ; 12:45
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of halogen substitutions (F, Cl, Br, and I) on the energy levels of the self-assembled hole-extracting molecule [2-(9H-Carbazol-9-yl)ethyl]phosphonic acid (2PACz), is investigated. It is found that the formation of self-assembled monolayers (SAMs) of [2-(3,6-Difluoro-9H-carbazol-9-yl)ethyl]phosphonic acid (F-2PACz), [2-(3,6-Dichloro-9H-carbazol-9-yl)ethyl]phosphonic acid (Cl-2PACz), [2-(3,6-Dibromo-9H-carbazol-9-yl)ethyl]phosphonic acid (Br-2PACz), and [2-(3,6-Diiodo-9H-carbazol-9-yl)ethyl]phosphonic acid (I-2PACz) directly on indium tin oxide (ITO) increases its work function from 4.73 eV to 5.68, 5.77, 5.82, and 5.73 eV, respectively. Combining these ITO/SAM electrodes with the ternary bulk-heterojunction (BHJ) system PM6:PM7-Si:BTP-eC9 yields organic photovoltaic (OPV) cells with power conversion efficiency (PCE) in the range of 17.7%-18.5%. OPVs featuring Cl-2PACz SAMs yield the highest PCE of 18.5%, compared to cells with F-2PACz (17.7%), Br-2PACz (18.0%), or I-2PACz (18.2%). Data analysis reveals that the enhanced performance of Cl-2PACz-based OPVs relates to the increased hole mobility, decreased interface resistance, reduced carrier recombination, and longer carrier lifetime. Furthermore, OPVs featuring Cl-2PACz show enhanced stability under continuous illumination compared to ITO/PEDOT:PSS-based cells. Remarkably, the introduction of the n-dopant benzyl viologen into the BHJ further boosted the PCE of the ITO/Cl-2PACz cells to a maximum value of 18.9%, a record-breaking value for SAM-based OPVs and on par with the best-performing OPVs reported to date.
|
|
| 3. |
- Peng, Wenhong, et al.
(författare)
-
Over 18% ternary polymer solar cells enabled by a terpolymer as the third component
- 2022
-
Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855. ; 92
-
Tidskriftsartikel (refereegranskat)abstract
- “Ternary blending” and “random terpolymerization” strategies have both proven effective for enhancing the performance of organic solar cells (OSCs). However, reports on the combination of the two strategies remain rare. Here, a terpolymer PM6-Si30 was constructed by inserting chlorine and alkylsilyl-substituted benzodithiophene (BDT) unit (0.3 equivalent) into the state-of-the-art polymer PM6. The terpolymer exhibitsadeep highest-occupied-molecular-orbital energy and good miscibility with both PM6 and BTP-eC9 (C9) and enables its use as a third component into PM6:PM6-Si30:C9 bulk-heterojunction for OSCs. The resulting cells exhibit maximum power conversion efficiency (PCE) of 18.27%, which is higher than that obtained for the optimized control binary PM6:C9-based OSC (17.38%). The enhanced performance of the PM6:PM6-Si30:C9 cells is attributed to improved charge transport, favorable molecular arrangement, reduced energy loss and suppressed bimolecular recombination. The work demonstrates the potential of random terpolymer as a third component in OSCs and highlights a new strategy for the construction of a ternary system with improved photovoltaic performance.
|
|
| 4. |
- Shen, Xinyi, et al.
(författare)
-
Chloride-Based Additive Engineering for Efficient and Stable Wide-Bandgap Perovskite Solar Cells
- 2023
-
Ingår i: Advanced Materials. - 0935-9648. ; 35:30
-
Tidskriftsartikel (refereegranskat)abstract
- Metal halide perovskite based tandem solar cells are promising to achieve power conversion efficiency beyond the theoretical limit of their single-junction counterparts. However, overcoming the significant open-circuit voltage deficit present in wide-bandgap perovskite solar cells remains a major hurdle for realizing efficient and stable perovskite tandem cells. Here, a holistic approach to overcoming challenges in 1.8 eV perovskite solar cells is reported by engineering the perovskite crystallization pathway by means of chloride additives. In conjunction with employing a self-assembled monolayer as the hole-transport layer, an open-circuit voltage of 1.25 V and a power conversion efficiency of 17.0% are achieved. The key role of methylammonium chloride addition is elucidated in facilitating the growth of a chloride-rich intermediate phase that directs crystallization of the desired cubic perovskite phase and induces more effective halide homogenization. The as-formed 1.8 eV perovskite demonstrates suppressed halide segregation and improved optoelectronic properties.
|
|
