Perovskite-inspired Cu₂AgBiI₆ for mesoscopic indoor photovoltaics under realistic low-light intensity conditions

Abstract

The considerable potential of perovskite-inspired Cu2AgBiI6 (CABI) photovoltaics under both solar and artificial lighting has been recently highlighted. However, to realistically ensure the suitability of CABI-based indoor photovoltaics (IPVs) to...

Antimony-bismuth alloying: the key to a major boost in the efficiency of lead-free perovskite-inspired indoor photovoltaics

“…The scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDS) maps of CABI and CABI-Sb samples (see Figure 1d) show a uniform distribution of Cu, Ag, Bi, Sb (for CABI-Sb sample), and I elements with overall compositions of Cu2AgBi0.71I4 (CABI) and Cu2.4AgBi0.69Sb0.15I4 (CABI-Sb). As earlier, 8,9 the lower (than nominal) bismuth and iodine values is attributed to small quantities of Cu2BiI5 and the evaporation of volatile iodine from the surface of the films during the heating process and the strong electron beam exposure. 8,26 The actual Bi:Sb ratio in the CABI-Sb sample according to the EDS analysis is ≈82:18, which is lower than the stoichiometric one (90:10).…”

“…The mesoscopic architecture was chosen since it is known to result in higher efficiencies than the planar counterpart for CABI-based devices. 9,17 The full device configuration, i.e., FTO|c-TiO2|mp-TiO2|absorber (CABI or CABI-Sb)|Spiro-OMeTAD|Au, relied on standard electron-(ETL) and hole-transport (HTL) layers, namely compact (c-) and mesoporous (mp-) TiO2 ETL and 2,2',7,7'-Tetrakis[N,N-di(4methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD) HTL (see Figure 5a). Figure S11 displays the cross-sectional view of a representative CABI-Sb device.…”

“…3,4 Perovskite-inspired pnictohalides employing cations from Group VA of the periodic table (e.g., antimony (III) (Sb 3+ ) and bismuth (III) (Bi 3+ )) have recently emerged as promising low-toxicity and highly stable absorbers for IPVs, owing to their bandgap of around 2 eV, which is nearly ideal for indoor light-harvesting. 5,6 However, so far only a small handful of IPV studies have been reported 5,7,8,9,10 with PCE(i) values already in the same range of commercially available hydrogenated amorphous silicon (a-Si:H) devices, 11,12 though still far from the maximum theoretical PCE(i) of 50-60%. 5,6 Indeed, all the reported PCE(i) values stagnate around 5-6% at 1000 lux white light-emitting diode (WLED) illumination, with the highest record being so far 6.4%.…”

“…13,14 Despite being one of the most recently discovered pnictohalides, Cu2AgBiI6 (CABI) has already gained an exceptional interest from the photovoltaic and optoelectronic community owing to its direct bandgap, high absorption coefficient, low exciton binding energy, and the desired band gap of ≈ 2 eV for IPVs. 8,9,15,16,17,18 Several works have contributed to improving CABI discontinuous morphology, consisting of small-sized grains and numerous cracks, by passivating the surface defects (e.g., via hydroiodic acid additive incorporation, 8 phenethylammonium iodide treatment, 18 or film deposition engineering 17 ). Nonetheless, the still suboptimal morphology of CABI films emphasizes the urgent need to enhance grain size and crystallinity.…”

Triple A‐Site Cation Mixing in 2D Perovskite‐Inspired Antimony Halide Absorbers for Efficient Indoor Photovoltaics

“…Under 1000 lux, the device delivers a champion PCE(i) of 6.37%, and the corresponding FF, J SC and V OC values are 52%, 102 µA cm −2 and 0.55 V, respectively. The 6.37% PCE(i) is the highest value ever reported for pnictohalides (5.52% [ 57 ] is the previous PCE(i) record, as shown in Table S5, Supporting Information). Figure 5c shows that the CsMAFA‐Sb devices exhibit an average PCE(i) of 5.06% at 1000 lux.…”