Interior/Interface Modification of Textured Perovskite for Enhanced Photovoltaic Outputs of Planar Solar Cells by an In Situ Growth Passivation Technology

Abstract

To compensate for the photoelectric losses of planar heterojunction perovskite solar cells (PSCs), the development of high-quality textured absorbers with excellent lightharvesting ability and carrier extraction/transfer efficiency is of great significance to achieve a high-efficiency stable photovoltaic output. In this paper, we propose an in situ growth passivation technique to construct high-performance textured absorbers by adding a 2-amino-4-chlorophenol (AC) modifier consisting of multiple groups during the growth of textured perovskite. Initially, according to the Ostwald ripening mechanism, the strongly polar dimethylformamide (DMF) was used as the etchant to systematically study its synergistic effect on the morphology evolution, crystallization kinetics, light-trapping capability, and photovoltaic loss of textured absorbers. An appropriate amount of DMF induces formamidinium cations (FA + ) to replace methylammonium cations (MA + ) in the perovskite lattice while etching the absorber to form a texture configuration, which effectively broadens the spectral absorption range, thus greatly improving the light-trapping capacity and short-circuit current density of planar PSCs. In contrast, excess DMF deteriorates the device performance due to the excessive corrosion of the perovskite. Moreover, the introduction of the AC modifier is of great significance for passivating deep-level defects and accelerating the charge extraction/ transfer. Owing to the electron-donating nature of the Lewis base, the hydroxyl groups with a higher electron density in AC molecules can better coordinate with Pb 2+ ion defects, which effectively improves the crystallinity of the textured perovskite, thus suppressing the nonradiative recombination and ultimately improving the photovoltaic outputs of modified devices, particularly the fill factor and the open-circuit voltage. Thus, the photovoltaic performance of the AC-modified planar PSC is significantly better than that of the conventional textured device, with a reverse efficiency of 21.18% and forward efficiency of 20.77%. Owing to the synergistic effect of (1) the superior optical properties of the textured perovskite induced by DMF and (2) excellent charge dynamics driven by AC, the functionalized devices without encapsulation also exhibited good photovoltaic output stability and reproducibility. This work provides novel insights into the growth mechanism of textured absorbers and paves the way for more efficient and stable planar PSCs.

Enhanced photovoltaic output of bifacial perovskite solar cells via tailoring photoelectric balance in rear window layers with 1T-WS2 nanosheet engineering

“…36,38 These results, which are consistent with the UPS and TRPL observations, suggest that the reduction in the energy band barrier induced by IT-WS 2 inhibits the heterointerface carrier aggregation and recombination, and effectively accelerates hole extraction/migration/collection, resulting in a significant improvement in the PV output of devices, especially short-circuit current density ( J SC ) and FF. 36–39…”

“…These terms correspond to the photoexcited charge carriers that are transported to the charge transport layer and undergo radiative decay, respectively. 36,37 The τ 1 and τ 2 of the perovskite/SP + W sample were both shorter than those of the perovskite/SP sample, reflecting that IT-WS 2 could promote carrier extraction/transfer/collection faster and more efficiently. The effects of different HTLs on the carrier extraction/recombination mechanisms in the PSCs were further analyzed using Nyquist plots measured at a bias voltage of 0.8 V in the dark.…”

“…In the EIS analysis, the R s derived from Ohmic or electrical contacts stands for the sheet resistance of the transporting layers and charge-transfer resistance at the interface; The R tr (fitted from the arc of the higher-frequency region) represents the heterointerface charge transfer and transportation resistance; The R rec (derived from the arc fitting of the lower-frequency region) is the resistance of charges annihilated at the interface or within the perovskite lattice. 33,34,36,38 The detailed parameters extracted from the fitting curves are summarized in Table S2 (ESI †). The R tr and R s values of the SP + W device are much smaller than those of the SP device, again confirming that IT-WS 2 enhances the charge dynamics at the perovskite/HTL interface.…”

“…The R tr and R s values of the SP + W device are much smaller than those of the SP device, again confirming that IT-WS 2 enhances the charge dynamics at the perovskite/HTL interface. 36,38 Moreover, the SP + W device features a higher R rec than that of the control SP device, reflecting a higher resistance for charge annihilation at the interface. 36,38 These results, which are consistent with the UPS and TRPL observations, suggest that the reduction in the energy band barrier induced by IT-WS 2 inhibits the heterointerface carrier aggregation and recombination, and effectively accelerates hole extraction/migration/collection, resulting in a significant improvement in the PV output of devices, especially short-circuit current density (J SC ) and FF.…”

“…36,38 Moreover, the SP + W device features a higher R rec than that of the control SP device, reflecting a higher resistance for charge annihilation at the interface. 36,38 These results, which are consistent with the UPS and TRPL observations, suggest that the reduction in the energy band barrier induced by IT-WS 2 inhibits the heterointerface carrier aggregation and recombination, and effectively accelerates hole extraction/migration/collection, resulting in a significant improvement in the PV output of devices, especially short-circuit current density (J SC ) and FF. [36][37][38][39] The synergistic relationships among the hybrid HTL, charge behavior, and PV parameters of the solar cells were further elucidated by open-circuit photovoltage decay (OCVD) and dark-current measurements.…”