How To Quantify the Efficiency Potential of Neat Perovskite Films: Perovskite Semiconductors with an Implied Efficiency Exceeding 28%

Abstract

Within the last years, perovskite semiconductors have been widely applied as active layers in thin film solar cells, as well as in many other opto-electronic devices such as light emitting diodes [1,2] and (photo) detectors. [3][4][5] Owing to their defect-tolerant nature and ease of fabrication from solution and/or vacuum deposition, [6] perovskites are the almost ideal candidate to be combined with already well-established commercial solar cell technologies such as monocrystalline silicon, [7] CIGS [8] but also with perovskite itself (all-perovskite tandem cells). [9] In the last few years, these properties enabled major research breakthroughs within a comparatively short time which has accelerated research on various PV technologies. For example, with respect to single-junction perovskite solar cells, the efficiency increased from 3.9% to 25.2% [10] within only 10 years and monolithic silicon/perovskite tandem cells reached up to 29.1% power conversion efficiency within an arguably even shorter Perovskite photovoltaic (PV) cells have demonstrated power conversion efficiencies (PCE) that are close to those of monocrystalline silicon cells; however, in contrast to silicon PV, perovskites are not limited by Auger recombination under 1-sun illumination. Nevertheless, compared to GaAs and mono crystalline silicon PV, perovskite cells have significantly lower fill factors due to a combination of resistive and non-radiative recombination losses. This necessitates a deeper understanding of the underlying loss mechanisms and in particular the ideality factor of the cell. By measuring the intensity dependence of the external open-circuit voltage and the internal quasi-Fermi level splitting (QFLS), the transport resistance-free efficiency of the complete cell as well as the efficiency potential of any neat perovskite film with or without attached transport layers are quantified. Moreover, intensitydependent QFLS measurements on different perovskite compositions allows for disentangling of the impact of the interfaces and the perovskite surface on the non-radiative fill factor and open-circuit voltage loss. It is found that potassium-passivated triple cation perovskite films stand out by their exceptionally high implied PCEs > 28%, which could be achieved with ideal transport layers. Finally, strategies are presented to reduce both the ideality factor and transport losses to push the efficiency to the thermodynamic limit.

A molecular photosensitizer achieves a Voc of 1.24 V enabling highly efficient and stable dye-sensitized solar cells with copper(II/I)-based electrolyte

“…To unravel the fundamental reasons for the substantial improvement of the performance by co-sensitization, we studied the major PCE loss mechanisms of the XY1b and MS5 + XY1b-based DSCs by analyzing the J − V curves (Supplementary Fig. 6 ) following a method inspired by Guillemoles et al and Stolterfoht et al 33 , 34 . The performance losses of J sc , V oc , and FF are summarized in Fig.…”

“…The qSQ J − V curve is then calculated from V oc,qSQ and J sc,qSQ using Eq. ( 2 ) 34 with the dark emission current being determined from the relation , where q is the elementary charge, k B the Boltzmann constant and T = 298 K the cell temperature (see Supplementary Fig. 6 and Supplementary Table 3 ).…”

Defect tolerant device geometries for lead-halide perovskites

“…While it has been coined in the context of computational material screening 6 , lead-halide perovskites were the first incarnation of a defect-tolerant semiconductor with an antibonding valence band that works particularly well in solar cells and light emitting diodes 5,7 . One of the key reasons for this success was that solution processed polycrystalline layers of lead-halide perovskites in a wide range of stoichiometries and with varying cations and halides showed long charge carrier lifetimes 9 , high luminescence quantum yields [10][11][12][13][14] and subsequently high opencircuit voltages [14][15][16][17] and efficiencies > 23% [18][19][20][21][22] if used as a solar cell. In most classical semiconductors intrinsic point defects (vacancy, interstitial, antisites) and other complex defects from unintended impurities (eg.…”

Choose Your Own Adventure: Fabrication of Monolithic All‐Perovskite Tandem Photovoltaics

“…While single‐junction perovskite cells currently have demonstrated the highest efficiencies among polycrystalline thin‐film PVs, they are likely to have a maximum practical efficiency of ≈28% PCE whereas all‐perovskite tandems have a clear path to well over 30%. [ 40,45 ] There has been a flurry of work on monolithic, 2‐terminal (2T) perovskite‐based tandems, pairing a wide‐ E g MHP with materials such as low‐ E g tin/lead (Sn/Pb) MHP, [ 4,36,46–52 ] copper indium gallium diselenide (CIGS), [ 9,53–55 ] GaAs, [ 56 ] or crystalline Si. [ 38,39,57–61 ] Tandem cell record efficiencies of 29.15% has been reported for a perovskite‐Si tandem, [ 9 ] 24.8% for an all‐perovskite [ 36 ] (Figure 1A) and 24.2% for a perovskite‐CIGS tandem, [ 9 ] all under AM1.5G simulated sunlight.…”