Introduction of a Novel Figure of Merit for the Assessment of Transparent Conductive Electrodes in Photovoltaics: Exact and Approximate Form

Abstract

Transparent conductive electrodes (TCEs) are key components of photovoltaic devices. Being transparent, they allow light to enter the device, and being conductive, they allow the photocurrent generated to be drawn into the outer electric circuit. Ideally, TCEs exhibit maximum light transmission and conductivity at the same time. However, both properties have to be balanced. Depending on the photovoltaic material system, the selection of the most suitable TCE is crucial and is assessed by so‐called figures‐of‐merit (FOM). Here, a novel and exact FOM that explicitly considers the impact on photovoltaic performance is proposed. This novel FOM exhibits several useful attributes, among them: i) proportionality to the potential power output of the photovoltaic device, ii) normalization with regard to the theoretically ultimately attainable photovoltaic performance and, thus, it provides above all iii) meaningful guidance for the development of advanced TCEs. Based on the exact FOM, the transition sheet resistance is defined as the parameter, which separates the so‐far unidentified two regimes of TCE operation: transmittance versus conductance limited. An overview of realized state‐of‐the‐art semitransparent electrodes is reassessed and compared herein. Furthermore, the TCE requirements for various photovoltaic material systems are assessed in dependence on the spectral range of their operation.

Advances in Flexible Metallic Transparent Electrodes

“…Chu et al have demonstrated that CuNW TEs (T = 90%, R sh = 52.7 Ω sq −1 , area > 50 cm 2 ) prepared by spray coating could be assembled as resistive TSPs. [73] Flexible transparent capacitive-force detection touch sensors based on UV-curable polyurethane acrylate (PUA) resincovered CuNW electrode were also recently demonstrated by Kim et al [425] Of note, the poor adhesion of MNW networks, their nonuniform topography, and instability against static electricity Small 2022, 18, 2106006 [412] with the impact of transmittance and sheet resistance on photovoltaic performance for the spectral range of [280, 1100 nm] and a solar cell length of 5 mm. Reproduced with permission.…”

Comment on “Introduction of a Novel Figure of Merit for the Assessment of Transparent Conductive Electrodes in Photovoltaics: Exact and Approximate Form”

“…recently published a figure of merit (FOM) for transparent conductive electrode (TCE) performance in solar cells. [ 1 ] Their FOM uses a detailed balance calculation for maximum power conversion efficiency of a solar cell with a given band gap ( E gap ) absorbing the air mass 1.5 global (AM1.5G) spectrum. They assume that series resistance in the TCE ( R TCE ) is [ 2,3 ] $$\[ \begin{array}{*{20}{c}}{{R_{{\rm{TCE}}}} = \frac{{{R_{{\rm{sh,TCE}}}} \cdot {L^2}}}{{3 \cdot A}}}\end{array} \]$$…”

“…Anand et al. consider monolithically integrated modules (Figure S1, Supporting Information [ 1 ] ) with cell lengths of L = 0.5 cm. However, they do not consider the optical deadspace of real monoliths, so their cells cannot be stacked side by side to form a module and their results do not scale to arbitrary areas.…”

“…In addition to uniform TCEs, Anand et al consider the transmittance-sheet resistance tradeoffs of patterned metal grids (called "AgNW 2 , CuNW 2 , Ag metal mesh, and nanotroughs" in their work). [1,14] However, metal grids have nonuniformity that induces resistance in the underlying semiconductor, so their merit deviates from that of uniform TCEs. [6] Therefore, coupling a uniform TCE with a metal grid changes TCE merit.…”

Стабильность функциональных характеристик прозрачных электродов на основе трехслойной структуры ZnO : Ga/Ag/ZnO : Ga

“…Ранее в 2019 г. нами была проведена оптимизация толщин оксидных слоев и серебряной прослойки для трех-слойной симметричной системы ZnO : Ga/Ag/ZnO : Ga (GAG) с целью достижения максимального критерия качества FOM (figure of merit) = T 10 av /R s (где T av -средний коэффициент оптического пропускания, R s -поверхностное сопротивление прозрачного электрода) [7]. Было показано, что трехслойная структура GAG, детали получения которой представлены в работе [8], при оптимизированных толщинах оксидных слоев d GZO = 40 nm и ультратонкого среднего слоя серебра d Ag = 10 nm (рис.…”