Prof Yen-Hung Lin

Abstract:

Monolithic all-perovskite tandem solar cells (TSCs) offer a route beyond single-junction efficiency limits through band-gap engineering. However, stability is hampered by hygroscopic degradation and phase segregation of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), the most common hole-transport material for narrow band-gap subcells. Here, we investigate the interface-mediated crystallization dynamics in mixed tin-lead (Sn-Pb) perovskites through in situ studies. We find that solvent-underlayer synergetic interactions with PEDOT:PSS induce metastable phase segregation during crystallization. Replacing PEDOT:PSS with a phenothiazine-functionalized interface facilitates direct phase transition and achieves preferential (100) orientation, yielding high-quality perovskite films. This enables a single-junction narrow band-gap subcell with 23.2% efficiency. Furthermore, we apply a hybrid interlayer integrating thiol and phosphonic acid anchoring groups on SnO2/Au, achieving a dense interconnecting layer for monolithic all-perovskite TSCs with 29.1% efficiency. The device retains 90% of the initial efficiency over 800 h of maximum power point tracking under simulated 1-sun illumination at 40°C, demonstrating robust operational stability.

Abstract:

The commercialization of perovskite solar cells (PSCs) is bottlenecked by inefficient trial-and-error approaches reliant on human expertise in both materials discovery and device fabrication^1-3. Here we introduce an autonomous closed-loop framework that integrates machine learning (ML)-driven materials discovery with an automated manufacturing platform. The system uses active learning and quantum modelling to rapidly identify high-performance molecules and the platform uses Bayesian optimization and symbolic regression in a feedback loop to continuously refine the fabrication process. This integrated approach enabled the discovery of a passivation molecule, 5-(aminomethyl)nicotinonitrile hydroiodide (5ANI), which yielded 0.05-cm² solar cells with a power conversion efficiency (PCE) of 27.22% (certified maximum power point tracking (MPPT) efficiency of 27.18%) and 21.4-cm² mini-modules with a PCE of 23.49%. Moreover, the devices exhibited long-term operational stability, retaining 98.7% of their initial efficiency after 1,200 h of continuous operation under the ISOS-L-1I protocol. Crucially, the automated platform achieved an efficiency reproducibility nearly five times that of manual fabrication. This work establishes an automated closed-loop system that synergizes ML-powered discovery with the high-fidelity data from automated manufacturing, setting a benchmark for autonomous discovery and manufacturing in photovoltaics and materials.

Abstract:

All-inorganic perovskite solar cells (PSCs) have emerged as a prominent research focus because the high thermal/photo stability they can offer is critical to commercialization of the burgeoning photovoltaic (PV) technology. However, there remain issues pertaining to the susceptibility of the all-inorganic perovskites to surface degradation from moisture ingress under ambient conditions and the suboptimal PV efficiency that still lags substantially behind that of their organic-inorganic hybrid counterparts. To address these challenges, this work employs an in situ self-assembly strategy to construct a 1D/3D perovskite heterojunction on top of the all-inorganic perovskite using tetrabutylammonium trifluoromethanesulfonate (TTFS). While typical ammonium salts only provide a cationic barrier or weak passivation, the TTFS-based design uniquely synergizes a hydrophobic cationic barrier with strong anionic passivation, and concurrently creates fast electron extraction channels through a nanostructured interface. This approach overcomes the conventional trade-off between stability and efficiency. By exploiting it to optimize a semi-transparent wide-band PSC for 4-terminal (4-T) tandem devices, a certified power conversion efficiency (PCE) of 17.10% was achieved together with exceptional operational stability under maximum power point (MPP) tracking-maintaining 80% of the initial PCE (T₈₀) after operating for 1210 hours at 65 °C and 650 hours at 85 °C (ISOS-L-2). When it is combined with a narrow-band all-inorganic PSC in the 4-T tandem configuration, a certified efficiency of 21.54% was obtained, which is the highest reported for this type of tandem cells. Through synergistic optimization of interface stabilization and tandem optoelectronic management, this work provides valuable insights for developing efficient and stable all-inorganic perovskite tandem solar cells.

Abstract:

Vacuum-based deposition is a scalable, solvent-free industrial method ideal for uniform coatings on complex substrates. However, all vacuum-deposited perovskite solar cells fabricated by thermal evaporation trail solution-processed counterparts in efficiency and stability due to film quality challenges, necessitating advancement and improved understanding. Here, we report a co-evaporation route for 1.67-eV wide-bandgap perovskites by introducing a PbCl2 co-source to optimize film quality. We promote perovskite formation with pronounced (100) “face-up” orientation and deliver a certified all vacuum-deposited solar cell with 18.35% efficiency (19.3% in the lab) for 0.25-cm2 devices (18.5% for 1-cm2 cells). These cells retain 80% of peak efficiency after 1,080 hours under the ISOS-L-2 protocol. Leveraging operando hyperspectral imaging, we provide spatiotemporal spectral insight into halide segregation and trap-mediated recombination, correlating microscopic luminescence features with macroscopic device performance while distinguishing radiative from non-ideal recombination channels. We further demonstrate 27.2%-efficient 1-cm2 evaporated perovskite-on-silicon tandems and outdoor stability of all vacuum-deposited tandems in Italy, retaining ~80% initial performance after 8 months.

Abstract:

Perovskite solar cells (PSCs) have reached power conversion efficiencies (PCEs) of 28%, but their scalable manufacturing remains hindered by the use of hazardous solvents and inert-atmosphere processing. Green-solvent air-processing is a promising route towards sustainable perovskite photovoltaics, yet its efficiency remains limited by an unresolved chemical bottleneck. Here we report that air-processing disrupts solvent–lead coordination in the precursor state, leading to intermediate-phase heterogeneity, defect formation, and non-uniform crystallization in dimethyl sulfoxide (DMSO)-based systems. We resolve this challenge by introducing a coordination-reconfiguration strategy in a green DMSO/isopropanol (IPA) solvent system using iodo-binaphthyl-sulfonimide (IBS) as a coordination-reconfiguring agent. Ab initio calculations and experimental results indicate that IBS preferentially binds PbI2, weakens the DMSO–PbI2 interaction, and reconfigures the precursor coordination environment, thereby suppressing air-disrupted solvated intermediates and enabling homogeneous crystallization of phase-pure perovskite films. The p–i–n PSCs processed from this system achieve PCEs of 26.51% in N2 and 26.20% in air, outperforming air-processed DMF/DMSO controls, while 13.3 cm² mini-modules deliver 23.20% PCE with strong operational and damp-heat stability.