Rubidium Multication Perovskite with Optimized Bandgap for Perovskite‐Silicon Tandem with over 26% Efficiency

Abstract

Rubidium (Rb) is explored as an alternative cation to use in a novel multication method with the formamidinium/methylammonium/cesium (Cs) system to obtain 1.73 eV bangap perovskite cells with negligible hysteresis and steady state efficiency as high as 17.4%. The study shows the beneficial effect of Rb in improving the crystallinity and suppressing defect migration in the perovskite material. The light stability of the cells examined under continuous illumination of 12 h is improved upon the addition of Cs and Rb. After several cycles of 12 h light–dark, the cell retains 90% of its initial efficiency. In parallel, sputtered transparent conducting oxide thin films are developed to be used as both rear and front transparent contacts on quartz substrate with less than 5% parasitic absorption of near infrared wavelengths. Using these developments, semi‐transparent perovskite cells are fabricated with steady state efficiency of up to 16.0% and excellent average transparency of ≈84% between 720 and 1100 nm. In a tandem configuration using a 23.9% silicon cell, 26.4% efficiency (10.4% from the silicon cell) in a mechanically stacked tandem configuration is demonstrated which is very close to the current record for a single junction silicon cell of 26.6%.

Large area efficient interface layer free monolithic perovskite/homo-junction-silicon tandem solar cell with over 20% efficiency

“…The p-n homo-junction on the front is formed by highly-doped boron diffusion. With regards to the top perovskite cell structure, although theoretically a band gap near 1.7 eV has been recommended in the absence of any optical loss, 29,30 parasitic absorption of short wavelengths exists in the hole transport materials (HTM) commonly used in state of the art solar cells 4,7,9,16,31 such as poly[bis(4-phenyl)(2,5,6-trimethylphenyl)]amine (PTAA), 4,9 and 2,2 0 ,7,7 0 -tetrakis(N,N-di-pmethoxyphenylamine)-9,9-spirobifluorene (spiro-OMeTAD). 4,31 Parasitic absorption of short wavelength light also exists in the ITO/MoO 3 stack, which is also the most commonly used transparent conductive stack for the top of the semi-transparent perovskite in a tandem.…”

Coated and Printed Perovskites for Photovoltaic Applications

“…[1] The material class of hybrid organic-inorganic perovskites combines excellent optoelectronic properties, such as long diffusion lengths [2] and short absorption lengths, [3] with the ease of solution processing, low energy payback times, and low-cost precursor materials. [8][9][10][11] Three key challenges hinder today the economical breakthrough of PSCs:Stability: First, the instability of PSCs against moisture, oxygen, light, and temperature limits the lifetime of PSCs to a fraction of the warranty lifetime (often >25 years) of the market dominating crystalline silicon (c-Si) PV. For example, the bandgap (E G ) can be tuned by changing the stoichiometric ratio of Br and I at the halogen anion site X.…”

Efficient Semitransparent Perovskite Solar Cells Using a Transparent Silver Electrode and Four-Terminal Perovskite/Silicon Tandem Device Exploration

“…For the four-terminal perovskite/ Si devices assembled by a perovskite top cell and Si bottom cell, many efforts were dedicated to search for an appropriate transparent electrode to replace the opaque metal rear contact normally used in PSCs. In most reports [17][18][19][20][21][22][23][24][25][26], the sputtered transparent-conductive-oxide (especially ITO) rear electrode has been commonly used, and the record overall efficiency of 26.4% has been achieved in the four-terminal devices with the perovskite top cell using the ITO/Au-finger electrode [18]. However, the sputtered ITO without postannealing (>200°C) treatment usually shows the suboptimal conductivity, and the high kinetic energy of sputtered particles tends to damage the underlying spiro-OMeTAD or fullerene layers [19]; thus, it is essential to increase the thickness (or add the finger electrodes) to compensate the resistive loss and deposit the buffer layer to protect the organic charge transport layers [18,20].…”

“…Simultaneously, the Si solar cells have dominated the photovoltaic markets for a long time, and the PCE record of the single-junction Si solar cell has reached 26.6% [8], but the relatively high manufactur-ing cost limits their wider applications. In recent years, the perovskite/Si tandem solar cells [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] have attracted increasing interest as they possess great commercial possibility in fabricating high-performance solar cells via the cost-effective pathway.…”