Solar RRL最新文献

Herein, we perform sequential deposition of the organic and inorganic sub-components evaporated from point sources, followed by thermal conversion to yield wide bandgap perovskite films for the application in perovskite/silicon tandem cells. In our approach, uniform formamidinium iodide (FAI) layers with varying thicknesses are first deposited with rotating substrate. We next co-evaporate the inorganic precursors PbI₂, PbBr₂, and CsI onto the FAI layer in a static mode, without substrate rotation, leading to thickness gradients across the substrate, known from single-layer characterization. To promote conversion to α-phase perovskite, another uniform FAI layer is deposited on top, sandwiching the inorganic precursor layer stack. After thermal conversion, we obtain controlled compositional variations of the perovskite layer. Using spatially resolved characterization techniques, the most suitable composition, hence, evaporation rates for the individual inorganic precursors and the best thickness of the FAI sublayer are identified in a time-efficient manner. As a result, an optimized average implied open-circuit voltage, iV_OC, of about 1230 mV and optical bandgap of 1.70 eV, very uniformly distributed over a half M6 wafer area, were achieved for the absorbers when deposited on a self-assembled monolayer. Without any perovskite surface passivation or additional treatment, single-junction devices with an average fill factor of 70% (65%) in reverse (forward) light current–voltage scan and V_OC of 1075 mV were achieved across several batches. Integrating this absorber in tandem cells with a random-pyramid textured bottom-cell led to preliminary cells with efficiencies up to 24%.

Wide-bandgap (WBG) perovskites have gained great attention as promising top-cell absorbers with the potential of enabling efficient perovskite/crystal silicon tandem solar cells (TSCs). However, defects generated during the deposition of perovskite substantially degrade device performance and operational stability. Here, we demonstrate an interfacial engineering strategy for efficient defect passivation of Cs_0.05(FA_0.77MA_0.23)_0.95Pb(I_0.77Br_0.23)₃ WBG perovskite (1.68 eV) films based on small organic molecule, benzylhydrazine monohydrochloride (BHC). The BHC, incorporating both primary amine (–NH₂) and protonated ammonium (–NH₃⁺) functional groups, enables bifunctional synergistic passivation of undercoordinated Pb²⁺ and cation vacancies on perovskite surface. This strategy boosts the power conversion efficiency (PCE) of WBG perovskite solar cells from 19.01% to 20.87%, with simultaneous improvements in all photovoltaic parameters including open-circuit voltage, short-circuit current density, and fill factor. Unencapsulated devices retain 80% of initial PCE after 960 h storage under ambient conditions. When integrated into perovskite/silicon TSCs, a PCE of 29.56% is achieved.

Salts based on bis(trifluoromethanesulfonyl)imide (TFSI) have been developed as additives for photoabsorbers in perovskite solar cells (PSCs) to enhance their photovoltaic (PV) performance. However, the effects of their TFSI anions have remained elusive. Herein, a novel methylammonium bis(trifluoromethanesulfonyl)imide (MA-TFSI) additive, comprising MA cations that are removed from the perovskite layer during heating, is verified. This is the first implementation of alkyl-primary-ammonium-based TFSI additives for perovskite layers. MA-TFSI addition exhibited unique chemical capping effects; the TFSI moieties were spontaneously coated on the outer surface of the perovskite and on the crystal grains during deposition, leading to the prevention of defect formation in the perovskite layer. Notably, the TFSI-capped perovskite surface displays high wettability to water droplets yet improved PV performance stability against humidity, contradicting the school of thought in the PSC research field. Parameter-differentiated contact angle (PDCA) measurements suggest that the high wettability of water droplets is attributed to the active hydrogen bonds derived from the TFSI capping. Meanwhile, the improved stability against humidity is attributable to the low dispersion energy of the CF₃ moiety in the TFSI capping on the crystal grains. The presented deviation from the prevailing viewpoint will lead to the advancement of materials science.

Polarization-type potential-induced degradation (PID-p) has become a risk for tunnel oxide passivated contact (TOPCon) solar cell modules. For the sake of intimating the long-term PID-p degradation of the modules under outdoor illumination, this study investigates the impact of different types and timing of illumination on the PID-p on the double-sided EVA encapsulated TOPCon modules: 1) multiple cycles of a PID test in the dark followed by a 2 kWh UV recovery; 2) PID tests under 170 W/m² UV illumination; and 3) PID tests under 800 W/m² simulated steady-state solar illumination. We find that all three testing methods lead to less power degradation than that in the dark after 96 h so that TOPCon photovoltaic modules will not suffer from severe PID-p risk in short term when running outdoors. After 672 h, the module subjected to PID tests under 800 W/m² simulated steady-state solar illumination shows the lowest degradation of −3.18%. This method more closely resembles the long-term outdoor operating conditions, where the module generating voltage under illumination forms a ground potential. Moreover, excessive UV irradiation in the testing method may exacerbate the UV-induced degradation issue and accelerate the aging of the encapsulant.

To maximize energy yield, photovoltaic (PV) system designers optimize parameters that enhance plane-of-array irradiance, with module tilt angle being a key factor. However, higher irradiation also raises operating temperatures, accelerating degradation mechanisms. While simulations offer insight, experimental validation is essential to assess tilt angle impacts on long-term reliability. This study presents an indoor accelerated aging test replicating variations in UV exposure linked to tilt angle. passivated emitter and rear contact (PERC) c-Si mini-modules underwent controlled UV soaking, elevated temperatures, and humidity to replicate prolonged outdoor conditions. Degradation was monitored through I–V curve measurements and electroluminescence imaging. Encapsulant discoloration and photobleaching primarily reduced short-circuit current (I_SC), while boron-oxygen light-induced degradation (BO-LID) and light and elevated temperature-induced degradation (LeTID) contributed to I_SC and open-circuit voltage (V_OC) losses. Further UV doses of 34, 17, and 6.5 kWh/m², representing different tilt angles, caused maximum power (P_max) reductions of 0.79%, 0.61%, and 0.35%, respectively. These results highlight the need for further study of BO-LID and LeTID in PERC and other c-Si PV technologies. The observed tilt angle effects cannot be generalized to long-term degradation. Further investigation into long-term impact by applying stabilization methods to the modules and afterward fitting the data to degradation models is needed to draw final conclusions.

To maximize energy yield, photovoltaic (PV) system designers optimize parameters that enhance plane-of-array irradiance, with module tilt angle being a key factor. However, higher irradiation also raises operating temperatures, accelerating degradation mechanisms. While simulations offer insight, experimental validation is essential to assess tilt angle impacts on long-term reliability. This study presents an indoor accelerated aging test replicating variations in UV exposure linked to tilt angle. passivated emitter and rear contact (PERC) c-Si mini-modules underwent controlled UV soaking, elevated temperatures, and humidity to replicate prolonged outdoor conditions. Degradation was monitored through I–V curve measurements and electroluminescence imaging. Encapsulant discoloration and photobleaching primarily reduced short-circuit current (I_SC), while boron-oxygen light-induced degradation (BO-LID) and light and elevated temperature-induced degradation (LeTID) contributed to I_SC and open-circuit voltage (V_OC) losses. Further UV doses of 34, 17, and 6.5 kWh/m², representing different tilt angles, caused maximum power (P_max) reductions of 0.79%, 0.61%, and 0.35%, respectively. These results highlight the need for further study of BO-LID and LeTID in PERC and other c-Si PV technologies. The observed tilt angle effects cannot be generalized to long-term degradation. Further investigation into long-term impact by applying stabilization methods to the modules and afterward fitting the data to degradation models is needed to draw final conclusions.

This study presents a machine learning-based design framework utilizing deep Q-learning (DQL) to optimize ultra-thin CdTe solar cells with active layer thicknesses ranging from 100 to 400 nm. By coupling the transfer matrix method for optical analysis with SCAPS-1D simulations for electrical modeling, the DQL agent effectively explored the complex parameter space, optimizing the thicknesses of all key layers, including SnO₂, CdS, CdTe, MoO₃, and Au. The DQL framework intelligently adjusted each layer based on electromagnetic wave propagation and absorption profiles, enhancing internal reflection and light trapping within sub-micron geometries. Even at extremely low absorber thicknesses (e.g., 100 nm), the optimized structures achieved high photovoltaic performance, with power conversion efficiencies up to 9.39% and J_sc values exceeding 11 mA/cm². At 400 nm, efficiency increased to 15.75% with J_sc of 20.86 mA/cm². These results demonstrate that efficient photon harvesting and carrier transport are achievable through full-stack optimization. External quantum efficiency and absorption spectra confirmed the integrated optical-electrical enhancement achieved by DQL. This work highlights the capabilities of reinforcement learning in high-dimensional solar cell design problems and provides a scalable approach for developing next-generation, lightweight, efficient, and material-conscious photovoltaic technologies.

This study presents a machine learning-based design framework utilizing deep Q-learning (DQL) to optimize ultra-thin CdTe solar cells with active layer thicknesses ranging from 100 to 400 nm. By coupling the transfer matrix method for optical analysis with SCAPS-1D simulations for electrical modeling, the DQL agent effectively explored the complex parameter space, optimizing the thicknesses of all key layers, including SnO₂, CdS, CdTe, MoO₃, and Au. The DQL framework intelligently adjusted each layer based on electromagnetic wave propagation and absorption profiles, enhancing internal reflection and light trapping within sub-micron geometries. Even at extremely low absorber thicknesses (e.g., 100 nm), the optimized structures achieved high photovoltaic performance, with power conversion efficiencies up to 9.39% and J_sc values exceeding 11 mA/cm². At 400 nm, efficiency increased to 15.75% with J_sc of 20.86 mA/cm². These results demonstrate that efficient photon harvesting and carrier transport are achievable through full-stack optimization. External quantum efficiency and absorption spectra confirmed the integrated optical-electrical enhancement achieved by DQL. This work highlights the capabilities of reinforcement learning in high-dimensional solar cell design problems and provides a scalable approach for developing next-generation, lightweight, efficient, and material-conscious photovoltaic technologies.

Ultraviolet (UV)-induced degradation is a critical issue for modern photovoltaic (PV) technologies such as passivated emitter and rear cell (PERC), tunnel oxide-passivated contact (TOPCon), and heterojunction (HJT) cell concepts. This study compares the stability against UV radiation of AlO_x/SiN_y stacks on mini-modules with p-type back junction solar cells. Our cells have a nondiffused textured front surface passivated with an AlO_x/SiN_y layer stack and feature passivating polysilicon on oxide rear contacts. We compare plasma-enhanced chemical vapor deposition (PECVD) and plasma-enhanced atomic layer deposition (PEALD) processes for the deposition of AlO_x layers using the same tube-type deposition system. After a UV dose of 146 kWh/m² using broadband UV lamps, modules with PECVD-AlO_x exhibit an efficiency loss of up to 27% while those with PEALD-AlO_x show minimal degradation of 2.5%. This comparison proves that the superior UV stability is achieved with the tube-type PEALD technique. Our findings thus show how UV stability can be improved without extra equipment dedicated solely to depositing ALD-AlO_x and without UV absorbing or down converting encapsulants.

Perovskite Solar Cells

In article number 2500319, Nopporn Rujisamphan and co-workers systematically investigate guanidinium halide salts (GuaX; X = I, Br, Cl) for mitigating charge accumulation at perovskite grain boundaries. They demonstrate that these salts modulate work function, passivate defects, and stabilize grain boundaries, resulting in improved grain uniformity, reduced trap density, enhanced carrier mobility, and suppressed ion migration–most pronounced with GuaCl.