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Silicon heterojunction (SHJ) solar cells have achieved a record efficiency of 26.81% in a front/back-contacted (FBC) configuration. Moreover, thanks to their advantageous high V OC and good infrared response, SHJ solar cells can be further combined with wide bandgap perovskite cells forming tandem devices to enable efficiencies well above 33%. In this study, we present strategies to realize high-efficiency SHJ solar cells through combined theoretical and experimental studies, starting from the optimization of Si-based thin-film layers to the implementation of electrodes with reduced indium and silver usage. Advanced opto-electrical simulations, which enable comprehensive theoretical understandings of the main physical mechanisms governing carriers' collection and light management, provide clear pathways for device designs and experimental optimizations. We present the fabricated FBC-SHJ solar cells in both monofacial and bifacial configurations with the best efficiencies of 24.18% and 23.25%, respectively. We point out that to achieve optimum device performance, the compositional materials should be holistically optimized and evaluated as part of the contact stacks with adjacent layers. As an outlook beyond the classical FBC-SHJ solar cell architecture, we propose various novel SHJ-based solar cell architectures. Their potential performance was assessed and compared via rigorous opto-electrical simulations and a maximal efficiency of 27.60% was simulated for FBC-SHJ solar cells featuring localized contacts. • Simulations guided efficiency improvement from 18% to over 24% for FBC-SHJ devices. • Understanding of transport mechanisms of charge carriers for SHJ solar cells. • Optimized monofacial and bifacial solar cells with reduced indium and silver usage. • Performance evaluation of various novel SHJ-based solar cell architectures. • A simulated efficiency of 27.60% for FBC-SHJ solar cells with localized contacts. [ABSTRACT FROM AUTHOR]

Transition metal oxide (TMO) thin films exhibit large bandgap and hold great potential for enhancing the performance of silicon heterojunction (SHJ) solar cells by increasing the short-circuit current density significantly. On the other hand, achieving precise control over the electrical properties of TMO layers is crucial for optimizing their function as efficient carrier-selective layer. This study demonstrates a general and feasible approach for manipulating the quality of several TMO films, aimed at enhancing their applicability in silicon heterojunction (SHJ) solar cells. The core of our method involves precise engineering of the interface between the TMO film and the underlying hydrogenated intrinsic amorphous silicon passivation layer by managing the reaction of the TMO on the surface. X-ray photoelectron spectroscopy spectra demonstrate that our methods can modify the oxygen content in TMO films, thereby adjusting their electronic properties. By applying this method, we have successfully fabricated WO x -based SHJ solar cells with 23.30 % conversion efficiency and V 2 O x -based SHJ solar cells with 22.04 % conversion efficiency, while keeping n -type silicon-based electron-transport layer at the rear side. This research paves the way for extending such interface engineering methods to other TMO materials used as hole-transport layers in SHJ solar cells. • Controlling the TMO/(i)a-Si:H interface using three methods: noPT, PT, and PTB. • PT method preserves oxygen content in TMO layers better than PTB and noPT methods. • PTB method maintains optimal TMO oxygen content regarding conversion efficiency. • PTB method enables 23.30 % efficiency and 80.80 % FF in WO x -based SHJ solar cells. • PTB method enables 22.04 % efficiency and 74.88 % FF in V 2 O x -based SHJ solar cells. [ABSTRACT FROM AUTHOR]

Solar‐assisted water electrolysis is a promising technology for storing the energy of incident solar irradiation into hydrogen as a fuel. Here, an integrated continuous flow electrochemical reactor coupled to a monolithic perovskite‐silicon tandem solar cell is demonstrated that provides light‐driven electrochemical solar‐to‐hydrogen conversion with an energy conversion efficiency exceeding 21% at 1‐Sun equivalent light intensity and stable operation during three simulated day‐night cycles. [ABSTRACT FROM AUTHOR]

The window layers limit the performance of silicon heterojunction (SHJ) solar cells with front and back contacts. Here, we optimized tungsten-doped indium oxide (IWO) film deposited by radio frequency magnetron sputtering at room temperature. The opto-electrical properties of the IWO were manipulated when deposited on top of thin-film silicon layers. The optimal IWO on glass shows carrier density and mobility of 2.1 × 1020 cm−3 and 34 cm2 V−1s−1, respectively, which were tuned to 2.0 × 1020 cm−3 and 47 cm2 V−1s−1, as well as 1.9 × 1020 cm−3 and 42 cm2 V−1s−1, after treated on i / n /glass and i / p /glass substrates, respectively. Using the more realistic TCO data that were obtained on thin-film silicon stacks, optical simulation indicates a promising visible-to-near-infrared optical response in IWO-based SHJ device structure, which was demonstrated in fabricated devices. Additionally, by adding an additional magnesium fluoride layer on device, the champion IWO-based SHJ device showed an active area cell efficiency of 22.92%, which is an absolute 0.98% efficiency gain compared to the ITO counterpart, mainly due to its current gain of 1.48 mA/cm2. • RF-sputtered IWO layer was optimized at room temperature. • Opto-electrical properties of IWO are manipulated by layers underneath. • The IWO-based SHJ device shows improved vis-NIR response than ITO cell. • By adding MgF 2 , the active area efficiency of IWO-based cell reaches 22.92%. [ABSTRACT FROM AUTHOR]

Low activation energy (E a) and wide bandgap (E g) are essential for (p)-contacts to achieve effective hole collection in silicon heterojunction (SHJ) solar cells. In this work, we study Plasma-Enhanced Chemical Vapor Deposition p -type hydrogenated nanocrystalline silicon oxide, (p)nc-SiO x :H, combined with (p)nc-Si:H as (p)-contact in front/back-contacted SHJ solar cells. We firstly determine the effect of a plasma treatment at the (i)a-Si:H/(p)-contact interface on the thickness-dependent E a of (p)-contacts. Notably, when the (p)nc-Si:H layer is thinner than 20 nm, the E a decreases by applying a hydrogen plasma treatment and a very-high-frequency (i)nc-Si:H treatment. Such an interface treatment also significantly reduces the contact resistivity of the (p)-contact stacks (ρ c, p), resulting in an improvement of 6.1% abs in fill factor (FF) of the completed cells. Thinning down the (i)a-Si:H passivating layer to 5 nm leads to a low ρ c, p (144 mΩ⋅cm2) for (p)-contact stacks. Interestingly, we observe an increment of FF from 72.9% to 78.3% by using (p)nc-SiO x :H layers featuring larger differences between their optical gap (E 04) and E a , which tend to enhance the built-in potential at the c-Si/(i)a-Si:H interface. Furthermore, we observe clear impacts on ρ c, p , open-circuit voltage, and FF by optimizing the thicknesses of (p)-contact that influence its E a. In front junction cells, the vertical and lateral collection of holes is affected by ρ c, p of (p)-contact stacks. This observation is also supported by TCAD simulations which reveal different components of lateral contributions. Lastly, we obtain both front and rear junction cells with certified FF well-above 80% and the best efficiency of 22.47%. • High E g (p)nc-SiO x :H and low E a (p)nc-Si:H bi-layer (p)-contact enables efficient, tunable selective transport of holes. • Optimized interface treatment significantly reduces the contact resistivity of (p)-contact stacks. • A larger difference between E 04 and E a of (p)nc-SiO x :H results in a notable improvement of hole collection. • TCAD simulation supports the understanding of lateral transport of holes in front junction solar cells. • Independently certified FF over 80% for both front and rear junction cells with the best efficiency up to 22.47%. [ABSTRACT FROM AUTHOR]