The efficiency of silicon solar cells has a large influence on the cost of most photovoltaics panels. Here, researchers from Kaneka present a silicon heterojunction with interdigitated back contacts reaching an efficiency of 26.3% and provide a detailed loss analysis to guide further developments.

Silicon heterojunction solar cell with interdigitated back contacts for a photoconversion efficiency over 26

With a global market share of about 90%, crystalline silicon is by far the most important photovoltaic technology today. This article reviews the dynamic field of crystalline silicon photovoltaics from a device-engineering perspective. First, it discusses key factors responsible for the success of the classic dopant-diffused silicon homojunction solar cell. Next it analyzes two archetypal high-efficiency device architectures – the interdigitated back-contact silicon cell and the silicon heterojunction cell – both of which have demonstrated power conversion efficiencies greater than 25%. Last, it gives an up-to-date summary of promising recent pathways for further efficiency improvements and cost reduction employing novel carrier-selective passivating contact schemes, as well as tandem multi-junction architectures, in particular those that combine silicon absorbers with organic–inorganic perovskite materials.

/pdf/high-efficiency-crystalline-silicon-solar-cells-status-and-47y1w8zg6w.pdf

High-efficiency crystalline silicon solar cells: status and perspectives

Photovoltaic solar cells based on metal halide perovskites have gained considerable attention over the past decade because of their potentially low production cost, earth-abundant raw materials, ease of fabrication and ever-increasing power conversion efficiencies of up to 25.2%. This type of solar cells offers the promise of generating electricity at a more competitive unit price than traditional fossil fuels by 2035. Nevertheless, the best research cell efficiencies are still below the theoretical limit defined by the Shockley-Queissier theory owing to the presence of non-radiative recombination losses. In this Review, we analyse the predominant pathways that contribute to non-radiative recombination losses in perovskite solar cells, and evaluate their impact on device performance. We then discuss how non-radiative recombination losses can be estimated through reliable characterization techniques, and highlight some notable advances in mitigating these losses, which hint at pathways towards defect-free perovskite solar cells. Finally, we outline directions for future work that will push the efficiency of perovskite solar cells towards the radiative limit.

Minimizing non-radiative recombination losses in perovskite solar cells

https://onlinelibrary.wiley.com/doi/pdf/10.1002/pip.2728

Solar cell efficiency tables (version 47)

https://onlinelibrary.wiley.com/doi/pdf/10.1002/pip.2788

Solar cell efficiency tables (version 48)

The crystalline silicon heterojunction structure adopted in photovoltaic modules commercialized as Panasonic's HIT has significantly reduced recombination loss, resulting in greater conversion efficiency. The structure of an interdigitated back contact was adopted with our crystalline silicon heterojunction solar cells to reduce optical loss from a front grid electrode, a transparent conducting oxide (TCO) layer, and a-Si:H layers as an approach for exceeding the conversion efficiency of 25%. As a result of the improved short-circuit current (J
 sc
), we achieved the world's highest efficiency of 25.6% for crystalline silicon-based solar cells under 1-sun illumination (designated area: 143.7 cm
 2
).

Achievement of More Than 25% Conversion Efficiency With Crystalline Silicon Heterojunction Solar Cell

A solar cell 70 includes: a base substrate 10 that has a principle surface; a first conductive-type layer 12n that is provided in a first region W1 on the principle surface; a second conductive-type layer 13p that is provided in a second region W2, which is different from the first region W1,on the principle surface; an n-side electrode 14 that is provided on the first conductive-type layer 12n; a p-side electrode 15 that is provided on the second conductive-type layer 13p; and grooves 31 and 32 that separate the n-side electrode 14 and the p-side electrode 15 from each other. The principle surface has an outer peripheral region C1 provided along the outer periphery of the principle surface and an inner region C2 provided inside the outer peripheral region C1. The respective widths W51 and W52 of the grooves 31 and 32 in a direction in which the n-side electrode 14 and the p-side electrode 15 are spaced apart are set to be wider in the outer peripheral region C1 than in the inner region C2.

Solar cell and solar cell module

A solar cell includes a photoelectric conversion body including one principal surface provided with a p-type surface and an n-type surface, a p-side electrode disposed on the p-type surface, an n-side electrode disposed on the n-type surface, and an insulating layer disposed between the p-side electrode and the n-side electrode and including a convex shaped surface.

Solar cell, solar cell module and method of manufacturing solar cell

Provided is a solar cell which has improved photoelectric conversion efficiency. A solar cell (1a) is provided with a photoelectric conversion unit (10), a p-side electrode (21p), an n-side electrode (22n) and an insulating layer (23). The photoelectric conversion unit (10) has a p-type surface (10bp) and an n-type surface (10bn) on one main surface (10b). The p-side electrode (21p) is arranged on the p-type surface (10bp). The n-side electrode (22n) is arranged on the n-type surface (10bn). The insulating layer (23) is arranged between the p-side electrode (21p) and the n-side electrode (22n). A surface (23a) of the insulating layer (23) is curved outward.

Tsutomu Yamaguchi

Papers

Achievement of More Than 25% Conversion Efficiency With Crystalline Silicon Heterojunction Solar Cell

Solar cell and solar cell module

Solar cell, solar cell module and method of manufacturing solar cell

Solar cell, solar cell module, and method for manufacturing solar cell